Triangle 

Mesh 

Concrete 

Reinforcement 



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Engineers' HandbooK 



American Steel & Wire Company 



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Handbook and Catalogue 



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Concrete 
Reinforcement 

Price $2.00 




American Steel & Wire Company 



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c4 9o- 






Copyrighted by 

American Steel & Wire Company 

February 3, 1908 






JUL 12 1923 




Contents 

PAGE 

Introduction . . . . . . . ' . . . 4, 5 

Reinforced Concrete ........ 6 

Economic Use and Properties of Reinforced Concrete, from 

" Reinforced Concrete," Buel & Hill 6-18 

Costs 19 

Approximate Cost of Concrete, from " Concrete, Plain and 

Reinforced," Taylor & Thompson ..... 19-21 

The Strength of Concrete ....... 21, 22 

Steel for Reinforcing . . . . . . . . 23-25 

Protection of Steel or Iron from Corrosion . . . 26-29 

Fire Protection, from " Concrete, Plain and Reinforced," 

Taylor & Thompson ........ 30-33 

Modulus or Coefficient of Elasticity ..... 31-36 

Bonding Old and New Concrete, from " Concrete, Plain and 

Reinforced," Taylor & Thompson ..... 37 

Effect of Freezing, from " Concrete, Plain and Reinforced," 

Taylor & Thompson . . . . . . . . 38, 39 

Classification of Cements, from " Concrete, Plain and Re- 
inforced," Taylor & Thompson . ..... 40-45 

Finishing Surfaces of Reinforced Concrete ... 46 

Facing and Finishing Exposed Concrete Surfaces, from 

"Reinforced Concrete," Buel & Hill 46-57 

Quantities of Materials ....... 58-65 

Theory of Reinforced Concrete . .... 66-68 

Explanation of Tables for Reinforced Concrete Slabs . 69-73 

Tables of Resisting Moments, Thickness of Slabs, Etc. . 74-86 

Illustrations Showing Thickness of Reinforcement . . 87 

Diagrams of Bending Moments for Slabs and Panels . 88, 89 

Reinforced Concrete Columns ...... 90-93 

Mechanics of Pipes and Rings Subject to External Pressure 94-102 

Typical Sewer Sections ........ 103, 104 

Illustrations Triangle Mesh Reinforced Concrete Pipe . 105-107 

Triangle Mesh Steel Wire Reinforcement with Illustrations 108, 109 

Tables of Weights, Areas and Sizes of Triangle Mesh 

Wire Reinforcement ....... 110-112 

American Steel & Wire Company's Steel and Iron W t ire 

Gage and Different Sizes of Wire .... 113 

Comparative Sizes Wire Gage in Decimals of an Inch . 114 

Table of Weights and Areas of Square and Round Bars, Etc. 115 

Illustrations of Uses of Reinforced Concrete . . . 116-126 

Report of Fire, Load and Water Test .... 127-145 



Introduction 

IN presenting this revised edition of our Engineers' Handbook and Catalogue 
on Triangle Mesh Reinforcement for Concrete we have attempted to touch 
. briefly not only the reinforcement for concrete but concrete itself. The 
data contained herein are the result of careful study by our engineering depart- 
ment, and also by some of the best known and accepted authorities. 

Many paragraphs and chapters dealing with reinforced concrete are selected 
and reprinted by permission from text books, bulletins and other publications, 
with due mention of the source and authority in each instance. 

Tables giving the weights of fabric per square foot, number, sizes, spacing 
and areas of wires and longitudinal strands of Triangle Mesh Woven Wire Rein- 
forcement are given on pages 110, 111 and 112, and tables of resisting moments, 
thicknesses of slabs, diagrams, etc., occur on pages 74 to 89 inclusive. 

By the use of Tables 1 to 12 inclusive (No. 1 being found on page 74), 
giving the resisting moments of reinforced concrete slabs, suitable fabric may 
be selected to use either with or without bars for all kinds of loads and spans 
and conditions met with in the construction of buildings, bridges and reinforced 
concrete in general. In these tables we have assumed different allowable 
stresses in the steel, namely, 16,000, 18,000 and 20,000 pounds per square 

M » 

inch, depending on its elastic limit, and different proportions of cement, sand 
and stone in the concrete. We, however, recommend in general using a 1:2:4 
mixture for floors or other structures subjected to high stresses. 

While we recommend the use of a fabric made with a steel having an 
ultimate strength of 85,000 pounds per square inch, we can furnish it in any 
strength of steel desired. 

Triangle Mesh Woven Wire Reinforcement for Concrete is made with either 
solid or stranded longitudinal members, properly spaced by means of diagonal 
or cross wires so arranged as to form a series of triangles between the longi- 
tudinal or tension members; the longitudinal members being invariably spaced 
4 inches apart, the cross wires either 2 inches or 4 inches, as desired, 
providing either a 2-inch or 4-inch mesh. The sizes of both longitudinals 



and cross wires are varied in order to provide the cross sectional areas of steel 
required to meet the conditions. 

Triangle Mesh Reinforcement, we believe, is the most efficient material 
on the market for the purposes : 

It provides a more even distribution of the steel, reinforcing in every 
direction. 

Tension or carrying members accurately spaced. 

A most perfect mechanical bond. 

When a specific size of fabric or area of steel is specified it is impossible 
to leave out any portion of the reinforcement. 

Minimum cost of installation. 

Easily handled and stored on the work. 

Low cost of inspection. 

An absolutely continuous action from one end of the structure to the other. 

Higher elastic limits with the same quality of steel due to cold drawing. 

Every ounce of steel is tested, as it cannot be cold drawn without showing 
defects, if any. 

Distributes the stresses due to a concentrated load over a greater area. 

Triangle Mesh Reinforcement is the only design of woven wire fabric in 
which the cross or diagonal wires assist the longitudinal or tension members in 
carrying the load. 

While reinforcing fabrics are made both galvanized and not galvanized, 
we strongly recommend the latter, due to the fact that a much better adhesive 
bond is provided and also greater strengths. In the case of a galvanized wire, 
the adhesion between the reinforcement and the concrete is to the coating on 
the steel and not to the steel itself, and also in the galvanizing process the steel 
is annealed or softened, thereby reducing its elastic limit and ultimate strength. 

It is a well-known fact that steel thoroughly imbedded in a proper mixture 
of concrete does not rust, and in the case of a smooth round rod used as 
reinforcement it is more desirable to have a thin surface coat of rust than 
if it were perfectly bright and smooth, provided the rust has not penetrated 
sufficiently far to pit the steel and produce a scale. This slight coating of rust 
provides a rougher surface and therefore a better bond. 



American Steel and Wire Company 



Reinforced Concrete 

In dealing with the uses and properties of reinforced concrete, we reprint, 
by permission, Chapter 1, from " Reinforced Concrete," by Buel & Hill: 

Chapter I 

Economic Use and Properties of Reinforced Concrete 

Concrete alone, considered as a building material, is nothing more nor 
less than a kind of masonry. The distinguishing features between rubble 
masonry and concrete are really confined to the methods of mixing and placing 
the materials. The results obtained with rubble masonry made of very small 
stone and with concrete made of large stone would be practically identical. 
The old Roman concrete was made with large stones, and may be classified 
either with rubble or concrete masonry. The value of either rubble or concrete 
as a material for construction depends largely on the quality of the cement 
used and the care exercised in the mixing and placing. Examples of masonry 
structures composed of large stones reinforced or tied together with iron rods 
and bars are found in the works of all periods, but usually only in connection 
with cut-stone masonry. The cost of such reinforcement was very great 
compared with the additional strength secured, and with rubble masonry the 
mechanical difficulties involved and the comparative cost render it impracticable. 

Reinforced Concrete With the advent of modern concrete the facilities with 

which reinforcing rods or bars of metal may be em- 
bedded anywhere in the mass of the masonry were soon seen and taken advantage 
of. The compressive resistance of concrete is about ten times its tensile resist- 
ance, while steel has about the same strength in tension as in compression. 
Volume for volume steel costs about fifty times as much as concrete. For the 
same sectional areas steel w r ill support in compression thirty times more load 
than concrete, and in tension three hundred times the load that concrete will 
carry. Therefore, for duty under compression only, concrete will carry a given 
load at six-tenths of the cost required to support it with steel. On the other 
hand, to support a given load by concrete in tension would cost about six times 
as much as to support it with steel. These economic ratios are the raison 
d* etre of reinforced concrete. If the various members of a structure are so 
designed that all of the compressive stresses are resisted by concrete, and steel 
is introduced to resist the tensile stresses, each material will be serving the 
purpose for which it is the cheapest and best adapted and one of the principles 
of economic design will be fulfilled. 

Other important advantages secured in the combination of concrete and 
embedded steel are that the protection of the metal elements from corrosion is 
practically perfect ; that, with properly selected ingredients, the fire and heat 
resisting qualities are very high, perhaps surpassed by no other building 
material except fire-brick, and, in many cases, that the substantial appearance 



Concrete Reinforcement 



of a masonry structure is obtained at about the cost of a more or less tem- 
porary unprotected steel structure. When intelligently reinforced with steel, 
concrete becomes a material suitable and economical for beams, floors and 
long columns, tanks, reservoirs, conduits and sewers ; admirably adapted to 
arch construction and often economical for dams and retaining walls. Even in 
concrete that is not subjected to tension or flexure it is often desirable to 
introduce steel reinforcement to prevent the occurrence of cracks due to shock 
or settlement, or other causes. 

Properties of Concrete A knowledge of the properties of materials is the 

first requisite for safe and economic designing of 
structures. The properties of reinforced concrete comprise not only those of 
the concrete and of the steel elements considered separately, but may be said to 
include those properties or characteristics of the composite mass that control 
the distribution of stresses between the elements of the combination of units 
and determine the nature of their inter-relation. Such properties as are required 
by the practical engineer or architect in intelligent designing are here assem- 
bled in concise form, with values assigned to them that are considered to be 
safe and conservative deductions from the most recent experiments accessible. 
The scope and purpose of this work does not permit of an elaborate exposition 
of all the recent experiments nor of an exhaustive discussion of the deductions 
to be drawn therefrom. 

Portland cement concretes only will be considered. Concrete made with 
natural slag, or Puzzolanic cements, although adapted to many uses, does not 
possess the qualities desirable for reinforced concrete structures, and all the 
experiments known to the writer, on which the theories of reinforced concrete 
are based, have been with Portland cement concretes. The object of reinforc- 
ing concrete with steel is to secure greater strength or safety, or both, than can 
be attained with concrete alone, and, excepting a few special cases where the 
concrete is used principally for a filling or to add mass to the construction, 
concrete made with Portland cement w 7 ill generally be found the most economical 
for equal strength, safety and durability. 

The properties of concretes vary with their age and with the proportions 
and quality of the ingredients. The values given here are for concretes made 
with (1) true Portland cement having a tensile strength per square inch neat, 
in seven days of 450 to 650 pounds, and in twenty-eight days of 540 to 750 
pounds ; (2) silica sand, not necessarily sharp nor coarse, but absolutely clean, 
and preferably a mixture of fine and coarse, and (3) good, hard, screened 
broken stone or clean gravel. The proportions of cement to sand generally 
used in the mortar or matrix, and for which there are reliable experimental 
data, vary from 1 of cement to 1 of sand up to 1 of cement and 6 of sand, 
and the proportion of mortar or matrix to the aggregate (broken stone 
or gravel) is from 100 to 110 per cent of the voids of the latter. 

This method of specifying the proportions, by cement to sand in the 
mortar or matrix and by mortar or matrix to voids in the aggregate, is 



American Steel and Wire Company 



here adopted because it is believed that the ratio of matrix to aggregate, where 
the latter is good clean material, does not affect the strength of the concrete 
except in so far as sufficient matrix should be provided to fill the voids in the 
aggregate. Other things being equal, the strength of the concrete will be pro- 
portional to the strength of the mortar, and the maximum strength for a given 
matrix or mortar will be attained when all voids are filled. In practice this 
requires a volume of matrix about 10 per cent in excess of the voids in the 
aggregate. Thus, if by mixing several sizes of broken stone or gravel, the pro- 
portion of voids to be filled is reduced from 45 per cent or 50 per cent 
down to 30 per cent, the proportion of matrix, cement and sand to aggre- 
gate may be considerably reduced without reducing the strength of the concrete 
or affecting its properties. Where cement or sand are dear and stone and 
gravel are cheap, advantage may be taken of this method to reduce the cost of 
the concrete very materially. 

The values here given are for concretes seven days, and one, three and 
six months old. Those values should be used which correspond to the age at 
which the structure may be subject to its full load. 

Compressive Strength Concrete is more often used in compression than in 

any other way, since it is more economical and has 
heretofore been considered more reliable under compressive strains than under 
transverse or tensile strains. Until very recent years engineers and architects 
hardly gave serious consideration to the value of concrete as a material to 
resist bending or tensile stresses, but at the present time comparatively few 
hesitate to use it in beams and similar situations, where it is partly subjected 
to tensile stress, and considerable number of eminent members of both pro- 
fessions have constructed works where the tensile strength of the concrete is 
taken advantage of. The best practice, where any tensile strains can occur, 
is to reinforce the section with steel. The two chief factors that determine 
the compressive strength of a concrete are its age and the proportion of sand 
to cement in the matrix. The quality of the cement, sand and aggregate have 
more or less influence on the resulting concrete, but with any good brand of 
modern high-burned Portland cement, clean sand and clean, hard stone, sub- 
stantially the same results may be secured. Factors of far greater weight are 
the manner and conditions of mixing and placing and the personal equation of 
the operator. On this account it is extremely difficult to harmonize or draw 
conclusions from the large number of isolated tests that have been made by 
independent investigators under widely varying conditions and often with 
different objects in view. 

A set of experiments made at the Watertown Arsenal for Mr. George A. 
Kimball, chief engineer of the Boston Elevated Railroad, in 1899, are the most 
homogeneous and systematic set of tests that have as yet been published, and 
are given in Table I. 

From these tests Mr. Edwin Thatcher has deduced formulas for the 
ultimate strength of concretes. They give results that agree with the average 



Concrete Reinforcement 



of the experiments and can be entirely relied upon for concretes carefully made 
from good materials. They are as follows : The ultimate compressive strength 
in pounds per square inch of concrete : 



Seven days old = 1,800 — 200 ( 

V 



volume of sand 



^volume of cemen 
One month old = 3,100 — 350 ( 
Three months old = 3,820 — 400 ( 
Six months old = 4,900 — GOO ( 
These formulas give the results shown in Table II 



d 



Tensile Strength The tensile strength may be safely placed at one-tenth of 
the compressive strength, and the modulus of transverse 

rupture. f= — at about 1 t G q that of the tensile strength. Tetmajer gives the 
o 

ratio as follows for Portland cement mortars consisting of 1 of cement to 3 of 
sand by weight : / compressive strength 



Tensile strength 



= (* 



61 + 1.8 log. of age in months 



) 



Shearing Strength M. Mesnagen states that the shearing strength of con- 
crete is from 1.2 to 1.3 times the tensile strength. 
Bauschinger gives the shearing strength of concrete four weeks old at 1.25 
times the tensile strength, and at two years old 1.5 times the tensile strength. 
A paper on the " Shearing Resistance of Reinforced Concrete," by S. Zipkes, 
translated by Mr. Leon S. MoisseifT, in " Cement," for March, 1906, gives the 
average shearing strength, at the appearance of the first cracks, at 81 pounds 
per square inch. At the time of rupture he found the average to be 357 
pounds per square inch. Prof. Moersch (" Cement," July, 1893) obtained an 
average shearing resistance of 400 to 440 pounds per square inch. Prof. 
Moersch's beams were tested at three months old, whereas Mr. Zipkes' speci- 
mens were all tested at an age of fifty days. Considering the difference in the 
age of the specimens, the agreement is fair. 

Table I 

Showing Compressive Strength of Concrete as Determined by Tests Made at Watertown 

Arsenal in 1899 



Mixture Is 2 : 4 



Brand of Cement 



Compressive Strength, Pounds per Square Inch 




Seven Days 

1,387 

904 

2,219 

1,592 

1 ,025 



One Month 
2,428 

2,420 
2,642 
2,269 

2,410 



Three Months 

2,966 
3,123 
3,082 
2,603 

2,944 



Six Months 

3,953 
4,411 
3,643 
3,612 

3,904 



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American Steel and Wire Company 



Mixture 1*3x6 



Brand of Cement 



Atlas . . 
Alpha . . 
Germania 
Alsen . . 

Average . 



Compressive Strength, Pounds per Square Inch 



Seven Days 



One Month 



1,050 

892 

1,550 

1,438 



1,232 



1,816 
2,120 
2,174 
2,114 



2,063 



Three Months 



2,538 
2,355 
2,486 
2,349 



Six Months 



3,170 
2,750 
2,930 
3,026 



2,432 



2,969 



Mixture I : 6 t 12 



Brand of Cement 



Atlas . 
Alpha . 
Germania 
Alsen . 

Average 



Compressive Strength, Pounds per Square Inch 



Seven Davs 



594 
564 
759 

417 



One Month 



1,090 

1,218 

987 
873 



583 



1,042 



Three Months 



1,201 

1,257 

963 

814 



Six Months 



1,066 



1,583 

1,532 

815 

1,323 



1,313 



Table II 

Showing Ultimate Compressive Strength of Concrete as Determined by Thacher's 

Formulas 









Age 






Seven Days 


One Month 


Three Months 


Six Months 


1 


: 1 


3 


1,600 


2,750 


3,360 


4,300 


1 


2 


4 
















1,400 


2,400 


2,900 


3,700 


1 


2y 2 


5 
















1,300 


2,225 


2,670 


3,400 


1 


3 


6 
















1,200 


2,050 


2,440 


3,100 


1 


'sy 2 


7 
















1,100 


1,875 


2,210 


2,800 


1 


4 


8 
















1,000 


1,700 


1,980 


2,500 


1 : 


5 


10 
















800 


1,350 


1,520 


1,900 


1 :6 


12 


COO 


1,000 


1,060 


1,300 



Table III 

Showing Modulus of Elasticity of Concrete as Determined by Tests at Watertown Arsenal 

in 1899 

Mixture 1 t 2 t 4 



Brand of Cement 



Atlas . 
Alpha 
Germania 
Alsen 



Average 



Modulus of Elasticity Between Loads of 100 to 600 



Seven Days 



2,778,000 



2,500,000 
2,500,000 



2,502,000 



One Month 



3,125,000 
2,083,0U0 

2,778,000 



2,662,000 



Three Months 



4,167,000 
4,167,000 
3,571,000 
2,778,000 



3,670,000 



Six Months 



3,125,000 
3,125,000 
4,167,000 
4,167,000 



3,640,000 



Concrete Reinforcement 



11 



Mixture 1: 3: 6 



Brand of Cement 



Modulus of Elasticity between Loads of 100 to 600 



Seven Days 



One Month 



Three Months 



Six Months 



Atlas . 
Alpha . 
Germania 
Alsen . 



Average 



1,677,000 



2,273,000 
1,667,000 



3,125,000 
2,083,000 
2,273,000 
2,273,000 



2,778,000 
3,571,000 
2,778,000 
2,778,000 



1,869,000 



2,438,000 



2,976,000 



3,571 ,000 
4,167,000 
3,125,000 
3,571,000 



3,608,000 



Mixture 1: 6: 12 





Modulus of Elasticity between Loads of 100 to 6l)0 




Seven Days 


One Month 


Three Months 1 Six Months 






1,316,000 

1,667,000 

961,000 

1,562,000 


1,136,000 
1,786,000 
2,083,000 
1,562,000 


1,780,000 
1,923,000 
1,786,000 
1,780,000 






1,376,000 | 1,642,000 1,820,000 



Modulus of Elasticity It has been said that no property of materials of 

construction is as uniform and reliable as the modu- 
lus of elasticity. This may be true of the modulus of elasticity of concrete, 
but the great variation in its value, as determined by the experiments hereto- 
fore published, has left the matter very much in the dark. Its value has been 
stated all the way from 750,000 to 5,000,000. This has been a discouraging 
condition for conservative constructors, and no doubt has greatly retarded 
the introduction of reinforced concrete in important works. The Watertown 
Arsenal tests in 1899 give values for the modulus of elasticity E of concrete 
as shown in Table III. 

From Table III the following formulas have been deduced, giving values 
very close to the averages of the experiments and sufficiently exact for all 
practical purposes. For concrete : 



7 days old, E = 2,600,000—700,000 f 



volume of sand \ 
volume of cement/ 

1 month old, E= 2,900,000— 300,000 ( do. — 1), 

3 months old, E= 3,600,000— 500,000 ( do. —2), 

6 months old, E= 3,600,000— 600,000 ( do. — 3), 

-rr ^ / volume of sand 

If the term 



-c \ is zero or less than zero (negative), the 



volume of cement 

entire term is to be considered zero. In other words, all negative values must 
be considered as zero. Table IV shows the moduli of elasticity as determined 
by the above formulas. These values are sufficiently reliable for all ordinary 



12 



American Steel and Wire Company 



purposes, and are probably as near to the truth as any that can be deduced 
from the experiments at present available. A large number of carefully 
executed experiments will be required to determine these values with greater 
precision. 



Table IV 

Showing Moduli of Elasticity of Concrete as Determined by Formulas 





Age 




Seven Days 


One Month 


Three Months . 


Six Months 


1:1 : 3 


2,600,000 


2,900,000 


3,600.000 


3,600,000 


1:2 


4 


2,600,000 


2,600,000 


3,600,000 


3,600,000 


1:2# 


5 


2,250,000 


2,450,000 


3,350,000 


3,600,000 


1:3 


6 


1,900,000 


2,300,000 


3,100,000 


3,360,000 


1:8# 


7 


1,550,000 


2,150,000 


2,850,000 


3,300,000 


1:4 


8 


1,200,000 


2,000,000 


2,600,000 


3,000,000 


1:5 


10 


500,000 


1,700,000 


2,100,000 


2,400,000 


1:6 :12 




1,400,000 


1,600,000 


1,800,000 



Mr. W. H. Henby has given forty-eight determinations of the modulus of 
elasticity under tensile stress and eighteen under compressive stress, but the 
conditions were varied so that they can only be compared in groups of two 
or three tests with constant conditions, and as would naturally be expected, 
the results were very erratic and are not conclusive. Professor Wm. H. Burr 
concludes that the same values may safely be used for the modulus of 
elasticity in tension as in compression. 

The values of E are only given for loads between 100 and 600, since 
these limits include the practical range of safe w r orking stresses per square 
inch. For purposes of computing the ultimate strength, which would be for 
loads from 600 to 4,000 pounds, E would have considerably lower values. For 
loads between 1,000 and 2,000 pounds the values would be from one-half to 
two-thirds of those given for loads between 100 and -600 pounds. For loads 
over 2,000 pounds satisfactory data are not known to the writer. Table V 
gives values of the modulus of elasticity for stresses up to 2,000 pounds per 
square inch as determined at the Watertown Arsenal in the series of tests 
made by Mr. George A. Kimball, Chief Engineer of the Boston Elevated Rail- 
road, in 1899. These determinations show that the modulus of elasticity is 
very much less at stresses between 1,000 and 2,000 pounds per square inch 
than between 100 and 600 and 1,000 pounds per square inch, but they are not 
sufficiently comprehensive to form the basis of any satisfactory rule or formula 
for the ratio of the modulus of elasticity to the stress per square inch. 



Concrete Reinforcement 



13 



Table V 

Showing reduction in value of E c with increasing loads. Values given are the mean of 
those for several experiments with several standard brands of Portland cement. 





Concrete 1. 2. 4. 


Concrete 1. 3. 6. 


Age 


100-000 


100-1,000 


1,000-2,000 


100-600 


100-1,000 


1,000-2,000 


Seven days 
One month 
Three months 
Six months 


2,592,000 
2,662,000 
3,670,000 
3,646,000 


2,053,000 
2,444,000 
3,170,000 
3,567,000 


1,351,000 
1,462,000 
2,157,000 
2,581,000 


1,869,000 
2,438,000 
2,976,000 
3,608,000 


1,529,000 
2,135,000 
2,656,000 
3,503,000 


1,219,000 
1,805,000 
1,868,000 



Professors Boeck and Melan found a value of E at about 750,000 in 
connection with the Austrian experiments, where a number of arches were 
tested to destruction. In calculations of ultimate strength by formulas, assumed 
values of E ranging from 1,500,000 to 750,000, according to the mixture, age, 
and the ultimate load per square inch would seem to agree more nearly with 
the average of previous experiments than values of E corresponding to loads 
much less than the ultimate strength. 

Two important points to be noted in connection with this subject are that 
the elastic limit of concrete, so far as it has been determined, is very close to 
the ultimate strength, and that its stress-strain diagram is a curve, instead of 
being practically a straight line as it is with steel inside of the elastic limit. 
The nature of this curve cannot be determined from the limited number of 
determinations that have been published. 

Working Loads In Table VI are -given what are considered safe working 
loads, in pounds per square inch, and properties for concretes 
in which the mortar or matrix is 1 of cement to >2 of sand and 1 of cement to 3 
of sand, and in which all the voids in the aggregate are filled. According to 
present practice, these mixtures will about cover the range for reinforced 
concrete. 

Properties of Steel The following properties of steel for use in computing 

reinforced concrete sections, with the values assigned 
to them, will be used herein. These values are believed to be safe, but may 
be varied as conditions require, according to the judgment of the designer: 

Ultimate strength, 58,000 to 66,000 pounds per square inch. 

Elastic limit, 55 per cent of the ultimate strength. 

Modulus of elasticity, 29,000,000. 

Working stress, factor of 4, 15,000 pounds per square inch. 

Working stress, factor of 5, 12,000 pounds per square inch. 

Rate of expansion per degree Fahrenheit, 0.00000G48 to 0.00000686. 

Relations Between Concrete and Steel The character of the relations that 

exist between the concrete and 
steel elements of reinforced concrete combinations depends first on the design 



14 



American Steel and Wire Company 



of the section. If the two elements act independently in resisting the stresses, 
so that either the one or the other might carry all the load, it may be called a 
composite design. 

If some of the forces are resisted entirely by the steel and other forces 
resisted entirely by the concrete, so that if the element resisting one force 
failed the entire section would fail, it may be called a combination design. 

If the disposition of the steel and the concrete in the section is such that 
the two elements act as a single unit, all stresses being divided between the 
concrete and the steel, where the latter occurs, and that the entire omission of 
the steel would only result in reducing the strength of the section, it may be 
called a true monolithic design. 

While many composite designs have been loosely classed with " concrete- 
steel," they really have little in common with the combination and monolithic 
designs. Since the concrete and the steel are independent of each other, and 
either one may carry all the load, it is clear that each element should be 
calculated independently and like an all-concrete or an all-steel section, as the 
case may be. This is not to imply that the concrete may not stiffen the steel 

Table VI 

Showing Safe Working Stresses for Concrete 



Mixture 


1 to 2 Matrix 


1 to 3 Matrix 


Age 


One Month 


Six Months 


One Month 


Six Months 


Safety factor 

Compression, pounds* 
Tension, pounds . . 


6 

400 

40 


5 

500 
50 


6 

600 

60 


5 

700 
70 


5 

340 

35 


5 

400 
40 


5 

500 

50 


5 

600 
60 


f-*L 

1 s 


64 


80 


96 


112 


56 


64 


80 


97 




50 


62 


75 


87 


44 


50 


62 


75 


E 


2,600,000 


3,600,000 


2,300,000 


3,360,000 



Rate of expansion ) 
per degree Fahr- .- 
enheit. ) 

Adhesion to iron ) 

or steel metallic >• 

surface, ultimate ) 
Safe working adhesion 60 to 100 pounds per square inch 



(Clark) .... 
(Rae and Dougherty) 
(Rae and Dougherty) 

(Bauschinger) . 
(Hatt) .... 



.00000795 

.00000655 for 1: 3: 5 concrete 
.00000561 for 1: 2 mortar 
570 to 640 pounds per square inch 
636 to 756 pounds per square inch 



*These values for compression are intended for use with the straight-line formulas only. 
For the formulas of the parbolic type they should be reduced, as the latter give larger 
moments of resistance ( M° ) than the straight-line formulas for the same value of com- 
pression in the extreme fibers (/c )• 

Note — Prof. Hatt also found that the friction of smooth round rods embedded in concrete 
after they started to slip was from 50 per cent to 70 per cent of the adhesion. 

For concrete not reinforced with steel, use two-thirds the values given in the tables 
for tension and_/= J/-J-.S. 



Concrete Reinforcement 15 



and prevent it from buckling, but as they do not act together as a combination 
or unit, and as the steel does not reinforce the concrete, except in the manner 
that any additional and independent section may reinforce another, designs of 
this type should scarcely be classed with concrete steel or reinforced concrete. 

Combination designs include concrete steel beams after the concrete on 
the tension side has been strained beyond the point of rupture, which will 
occur in a well-designed beam long before the ultimate strength of the beam 
is reached. Concrete beams reinforced with steel, under loads that produce 
maximum tensile stresses in the concrete less than the ultimate strength, act 
as a single unit and may be classed as monolithic. 

The most important characteristics or properties required to determine 
the distribution of stresses between the concrete and steel are the relations 
existing between the following: 

Ac = area of the section of the concrete. 
A s = area of the section of the steel. 
F c = the modulus of elasticity of the concrete. 
F s = the modulus of elasticity of the steel. 
Under direct compression or tension the stresses will be distributed between the two 
elements in the proportion of F c : F s : : A c F c : A s F S) where 

F c = the total stress in the concrete 
and 

F s =r the total stress in the steel. 
From this is derived the equation 

* = *.£%■ ■ ••••(!) 

F F s 

and if /c = — =- = the stress per square inch in the concrete and y s = — — = the stress per 
A c A c 

square inch in the steel, we have 

A=/c~- (2) 

which is to say that the stress per square inch in the two elements is directly 
proportional to their respective moduli of elasticity. This is derived directly 
from the definition of the modulus of elasticity which is the ratio of the stress 
per unit of section to the deformation. When the modulus of elasticity for 
steel is stated to be 29,000,000, it means that one pound per square inch 
tension or compression will stretch or compress the section an amount equal 
to its length divided by 29,000,000, and if E c , for the concrete, is 1,933,333, 
one pound per square inch will stretch or compress it an amount equal to its 

length divided by 1,933,333. If ^ = 2 ^°'^ = 15, and if the same 

jfo c l,9ob,ooo 

intensity of stress per square inch exists in both the concrete and the steel, the 



16 American Steel and Wire Company- 

concrete will be deformed fifteen times as much per unit of length as the steel, 
or in the ratio^- If, however, the stress per square inch in the steel is fifteen 

times that m the concrete, or in the ratio of E s \ E c , then the deformation will 
be the same per unit of length in both. Unless this latter condition maintains 
in every part of a concrete and steel structure of any description the surfaces 
of the two elements in contact will slide over each other or the concrete near the 
steel element will be strained beyond its elastic limit or its ultimate resistance. 
While it is the invariable practice to meet this condition in the design of 
arches, columns, etc., concrete steel beams are quite generally designed on the 
theory that the steel does all the work on the tensile side of the neutral axis. 
There is no doubt whatever that the concrete on the tensile side of a well- 
designed reinforced concrete beam will fail long before the ultimate strength 
of the beam is reached, since most all of the tests to destruction have demon- 
strated it to be so. This theory will be treated at some length in the chapter 
on beams. 

Coefficient of Expansion The thermal changes in reinforced concrete have 

ceased to be a matter for discussion from a prac- 
tical view-point, and have been relegated to the laboratories for the determination 
of the last decimal in the rates of expansion. Some of the most recent and 
reliable determinations made by Rae and Dougherty at Columbia University 
and by Prof. W. D. Pence at Purdue University gave the rate of expansion for 
Portland cement concrete with various proportions of sand and stone or gravel, 
such as are generally used in practice, at 0.00000545 to 0.00000655 per 
degree Fahrenheit. The later value by Rae and Dougherty is perhaps the more 
reliable, as the experiments were conducted with great care. Clark gives the 
rate at 0.00000795, which averaged with the mean of Prof. Pence's deter- 
mination, 0.00000545, gives 0.00000(370. This is less than 2}4 per cent 
greater than the value given by Rae and Dougherty. 

The rate of expansion per degree Fahrenheit for wrought-iron and steel is 
given by Kent at 0.00000648 to 0.00000686, and by U. S. reports on iron 
and steel at 0.00000617 to 0.00000676. The mean of these is about 
0.00000657. From this it appears that the difference in the rate for concrete 
and for steel is only a fraction of 1 per cent. 

Aside from this the large number of reinforced concrete structures that 
have been exposed to the weather in severe climate for years without any 
indication of injurious effect from thermal changes is a sufficient proof that if 
there is any difference in the rate for the two materials, it is not enough to be 
of consequence. 

Adhesion Between Next in importance to the ratio between the stress per 
Concrete and Steel square inch and the moduli of elasticity is the adhesion 

between the concrete and the steel. Table VI gives the 
ultimate and safe working values of this property in pounds per square inch. 
In the design of any combination or monolithic member of reinforced concrete 
the bond between the two elements is of vital importance. In the majority of 



Concrete Reinforcement 17 



cases met in practice, the relation between the elements is such that the entire 
stress in the steel must be transmitted to it by this bond of adhesion. When 
the shear per foot run between the steel and concrete exceeds the safe working 
adhesion, resort must be had to a mechanical bond. Various devices have 
been used to obtain an effective bond, such as corrugating or twisting square 
or flat rods or bars, driving rivets in flat bars, the projecting heads of which 
serve the purpose, and deforming round rods so that they are made up of 
alternate round and flat sections, but with the same sectional area at every point. 

Some engineers have objected to the use of square or flat sections on the 
ground that the sharp re-entering angles formed in the concrete weaken the 
latter and induce cracks to start from the angle when subjected to loads or 
shocks. In cast-iron, a material that has several properties similar to those of 
concrete, re-entering angles greatly weaken the sections, and therefore castings 
are generally boldly filleted at such angles. The writer does not know of any 
tests that throw light on this question, but notwithstanding the fact that 
considerable concrete has been reinforced with square and flat steel, it would 
seem to be safer and conservative practice to avoid all sharp re-entering angles 
in concrete. By far the larger part of all the reinforced concrete in Europe 
has been made with round rods or wires. In some cases steel angles, I-beams, 
or T's have been used, but squares and flats, if used at all, do not seem to 
have met with general favor. Tests more recently made in America indicate 
a considerable gain in ultimate strength of reinforced-concrete beams when rods 
are used that give a mechanical bond, as compared with beams made with plain 
rods. 

As this second edition is just going to press, reports on the effect of the 
California earthquake on buildings of different types of construction are just 
beginning to come in. These are as yet too meagre to form the basis of any 
conclusion. It is worthy of note, however, that the buildings with steel frames 
have stood the test very well, and that of the Leland Stanford University 
buildings, at Palo Alto, the damage was confined almost entirely to those with 
brick or stone masonry walls, while some buildings with monolithic concrete 
walls, not reinforced, escaped with little or no injury. Some of these buildings 
had concrete floors, reinforced with twisted rods, which are reported to have 
stood the test satisfactorily. It would seem to be prudent, in designing rein- 
forced concrete buildings, in localities subject to earthquake, to plan the 
reinforcing steel members so that they would be everywhere tied together and 
of such strength that they would be in stability without assistance from the 
concrete. 

The late Mr. Geo. S. Morrison, in an address approving the principle of 
reinforced concrete, referred to such construction as "concrete structures with 
metal structures inside." If the writer interprets this correctly, Mr. Morrison 
referred to structures in which the metal elements alone would form a complete 



18 American Steel and Wire Company 



and stable structure, though not necessarily one of sufficient strength to carry 
the required loads. This conception of a reinforced concrete structure seems 
to the writer to be the correct one, but, of course, it is not the cheapest that 
can be built. Many errors are made in attempting to keep down first cost, 
and such errors enter into a larger proportion of the structures built during the 
early stages of the development of any new method or system of construction 
than they do afterwards. As an example of this, all of our early metal bridges 
in the United States were built too light, even for the loads then in vogue, and 
we have come to adopt much heavier details than would previously have been 
used for the same duty. The writer believes that this applies with a special 
force to reinforced concrete construction and that the development of design 
will tend toward the idea of making the embedded metal parts at least capable 
of supporting themselves in their position in the structure without assistance 
or connections from the concrete in which they are to be embedded. Of 
course this does not refer to all kinds of structures, but more especially to 
reinforced concrete buildings. The Melan system of arch construction is a 
good illustration of this idea, as its reinforcement consists of a perfect metal 
arch, which is, in stability, without any assistance from the concrete and is 
sometimes made sufficiently strong to carry the entire load. 



Concrete Reinforcement 19 



Costs 

In considering a material to be used in building, one of the first things 
that an owner asks is, " What is the cost? " and usually this means the first cost, 
forgetting to consider the most important factor, the cost of maintenance and 
repairs, and the insurance, which runs on year after year. 

The first is practically the whole cost in using reinforced concrete, as 
compared to other building materials, and this varies according to the character 
of the construction and the purchase price of materials. 

The following paragraphs selected from page 24 of Taylor & Thompson's 
volume, " Concrete, Plain and Reinforced," contain some interesting data : 

Approximate Cost of Concrete 

The cost of concrete depends more upon the character of the construc- 
tion and the conditions which govern it than upon the first cost of the 
materials. In a very general w 7 ay we may say that w r hen laid in large masses 
or in a very heavy wall, so that the construction of the forms is relatively a 
small item, the cost per cubic yard in place is likely to range from $4 to $7. 
The lower figure represents contract work under favorable conditions with 
low prices for materials, and the higher figure small jobs and inexperienced 
men. Similarly, we may say that for sewers and arches, where centering is 
required, the price may range from $7 to $14 per cubic yard. Thin building 
walls, under eight inches thick may cost from $10 to $20 per cubic yard, 
according to the character of construction and the finish which is given to 
the surface.. 

These ranges in price seem enormous for a material which is ordinarily 
supposed to be handled by unskilled labor, but it must be borne in mind that 
skilled workmen are required for constructing forms and centers, and often 
the labor upon these may be several times that of mixing and placing the 
concrete. As a rule, unless the job is a very small one or under the personal 
supervision of a competent engineer, it is cheaper and more satisfactory to 
employ an experienced contractor than day labor. Green men under an 
inexperienced foreman may not be counted upon to mix and lay over one-half 
the amount of concrete that will be handled by a skilled gang under expert 
superintendence. 

A close estimate of cost may be reached, in cases where the conditions 
are known in advance, by taking up in detail and then combining the various 
units of the material and labor as outlined below. 

Cost of Cement As the price of Portland cement varies largely with the 
demand, it is necessary to obtain quotations from dealers 
for every purchase. It is such heavy stuff that the freight usually enters 
largely into the cost, and quotations should therefore be made f. o. b. the 
nearest point of delivery to the work. The cost of hauling by wagon may be 



20 American Steel and Wire Company 

readily estimated by assuming that a barrel of cement weighs 400 pounds 
(gross) , and that a pair of horses will haul over an average country road a load 
of, say, 5,000 pounds, traveling in all a distance of 20 to 25 miles in a day, 
that is, 10 to 12 }4 miles with load. This assumes, of course, that the teams 
are good and properly handled. 

Having found the cost of the cement per barrel, delivered, the approxi- 
mate cost per cubic yard is at once obtained from the table on page 17. If, 
for example, the cost is $2 per barrel and proportions 1:2^:5 are selected, the 
cost of the cement per cubic yard of concrete will be 1 . 29 X $2 . 00 = $2 . 58. 

Cost of Sand The cost of sand depends chiefly upon the distance hauled. 
~~~ " With labor at 15 cents per hour, the cost of loading (including 

the cost of the cart waiting at pit) may be estimated, if handled in large 
quantities, at 18 cents per cubic yard, or on a small job a.t 27 cents per cubic 
yard. For hauling add one cent for each 100 feet of distance from the pit. 
The additional cost of screening, if required, will vary with the coarseness of 
the material, but 15 cents per cubic yard may be called an average price for 
this, unless the sand is obtained by screening the gravel, when no allowance 
need be made. After finding the cost of one cubic yard of sand, the cost of 
the sand per cubic yard of concrete is readily figured from the table referred 
to. If, for example, the cost of sand screened, loaded and hauled 1,000 feet 
is 52 cents per cubic yard, the cost per cubic yard of concrete for proportions 
1:2^:5 will be 0.45 X $0.52 = $0.23%. 

Cost of Gravel If broken stone is used upon a small job for the coarse 
or Broken Stone aggregate, it is usually purchased by the ton or cubic yard. 
^ j^ 2000-lb. ton of broken stone may be considered as 

averaging approximately . 9 cubic yard, although differences in specific 
gravity cause considerable variation. A two-horse load is generally con- 
sidered 1)4 to 2 yards, the latter quantity requiring very high sideboards. 
The cost of screening gravel, if this is necessary, while a very variable item, 
may be estimated at 35 cents per cubic yard. The cost of loading gravel 
into double carts, with labor at 15 cents per hour, may be estimated on a 
small job at 38 cents per cubic yard. If handled in large quantities 25 cents 
is an average cost. The costof loading includes loosening and also the cost 
of the cart waiting at the pit. Hauling costs about one cent per cubic yard 
additional for each 100 feet of distance hauled under load. If, to illustrate, 
the cost of gravel picked, screened, loaded and hauled 1000 feet is 83 cents 
per cubic yard, the cost of the gravel per cubic yard of concrete for propor- 
tions 1:2% :5 will be . 91 X $0 . 83 = $0 . 75% . 

For distances up to 300 feet both sand and gravel can be hauled more 
economically by wheelbarrows than by teams. The cost of loading wheel- 
barrows is about half the cost of loading carts, while the cost of hauling with 
barrows per 100 feet is about four times greater. 

Cost of Labor With an experienced gang working at the rate of 15 cents 

___ ^^ hour, the cost of mixing and laying concrete, if shoveled 

directly to place from the mixing platform, will average about 80 cents per 



Concrete Reinforcement 21 



cubic yard, in addition to the work on forms. If, as is usually the case, the 
concrete is wheeled in barrows, 9 cents per cubic yard must be added to the 
above price for the first 25 feet that the barrows are wheeled under load, and 
1}( cents for each additional 25 feet wheeled. With other rates of wages, 
the cost may be considered as proportional. With a green gang the cost will be 
nearly double the above figures, but as the men become worked in and organi- 
zation perfected, the cost should approximate more nearly the prices given. 

The labor on forms is not included in the above. This is an extremely 
variable item. The cost of building rough plank forms (not including cost of 
lumber) on both sides of a 5-foot wail may be as low as 14 cents per cubic 
vard of concrete, with other thicknesses of wall in inverse proportion. On 
elaborate work the price, which is really dependent upon the face area, may 
reach several dollars per cubic yard of concrete. 

The Strength of Concrete 

The strength of concrete varies (1) with the quality of the materials ; (2) 
with the quantity of cement contained in a cubic yard of the concrete ; and 
(3) with the density of the mixture. 

We may say that the strongest and most economical mixture consists of 
an aggregate comprising a large variety of sizes of particles, so graded that 
they fit into each other with the smallest possible volume of spaces or voids, 
and enough cement to slightly more than fill all of these spaces or voids 
between the solids of the aggregate. It is obvious that with the same aggre- 
gate the strongest cement will make the strongest concrete. 

On important construction the various materials to be used should be 
carefully tested, and specimens of the mixture selected made up in advance 
and subjected to test. As a guide to the loads which concrete will stand in 
compression — that is, under vertical loading where the height of the column 
or mass is not over, say, 12 times the least horizontal dimension — we may 
give the following approximate figures as safe strengths, after the concrete 
has set at least one month, for the proportions which have previously been 
selected in this article as typical mixtures. , 

The figures, compared with the result of recent experiments on 12-inch 
cubes, allow a factor of safety of six at the age of one month, or eight at the 
age of six months, and are based on conservative practice. The relative 
strengths of the different mixtures are calculated from original investigations of 
the authors discussed in Chapter XIII. 

Safe Strength of Portland Cement Concrete in Direct Compression 



Proportions 



Pounds per 
Square Inch 



Tons per 
Square Foot 



1:2:4 410 29 

1:2^:5 360 25 

1:3:6 325 23 

1:4:8 : 260 18 




With a large mass foundation, take values one- eighth greater. 
With a vibrating or pounding load, take one-half these values. 



22 American Steel and Wire Company 

The tensile strength of concrete is very much less than the compressive 
strength. Experiments made by the authors, with mixtures of average pro- 
portions, give the ultimate fiber stress in beams as about one-eighth the 
breaking strength in compression. 



Concrete Reinforcement 23 

Steel for Reinforcing 

While there may or may not be advantages in using a high carbon, high 
tensile strength steel in reinforcing concrete, the opinion in general seems to 
be in favor of a medium or mild steel. A tensile strength of 64,000 pounds 
per square inch is about the minimum breaking point of ordinary mild com- 
mercial steel, while high carbon, high tensile strength steel will often run as 
high as 150,000 pounds per square inch, and if used less steel is required. 
But owing to the brittle nature of high carbon steel, as well as the difficulty in 
securing a uniform quality, it appears more dangerous to use. 

The coefficient or modulus of elasticity being one of the governing factors 
in reinforcing concrete, and this remaining the same in either a high or low 
carbon steel, it is usually more desirable to use a mild or commercial steel for 
reinforcing purposes. 

We reprint below, by permission, on this subject, " Quality of Reinforcing 
Steel," from page 291, "Concrete, Plain and Reinforced," by Taylor & 
Thompson : 

Quality of Reinforcing Steel It is generally recognized that in beam design 

the yield point of the steel shall be considered 
as the point of failure of this material in a reinforced beam. Tests show that 
when the metal reaches its yield point, the beam sags, and this deflection, due 
to the stretch of the steel and in some cases to the slipping of the steel be- 
cause of its reduced cross section, is likely to produce crushing in the concrete. 

The yield point of ordinary mild steel purchased in the open market, as 
determined by the drop of the beam in testing (the true elastic limit is several 
thousand pounds lower), cannot safely be fixed at a higher value than 30,000 
pounds per square inch, although frequently, and in fact in the majority of 
cases, a value of at least 36,000 pounds and in many cases 40,000 pounds, 
will be found. 

High steel, that is, steel containing a high percentage of carbon, has a 
much higher yield point than mild steel. If of first-class quality,* a minimum 
yield point may be placed at 50,000 or 55,000 pounds per square inch, and 
much of it will reach 60,000 pounds. The ultimate strength should be not 
less than 105,000 pounds per square inch. Thus, if it can be safely employed 
in reinforced concrete, it is adapted to carry much higher stress than mild 
steel, and, conversely, a smaller percentage of it is required for the same mo- 
ment of resistance. Many engineers do not approve of the use of high steel 
because of its brittleness, when of poor quality, and the danger of sudden 
accident, and because of the fact that it is prohibited in ordinary structural 
steel work. 

Mild steel, that is, ordinary market steel, is manufactured and sold under 
such standard conditions that it may be safely used without test. High steel, 
on the other hand, mast be very thoroughly tested. When tested, however, as 
per our specifications, page 38, it is entirely safe and to be preferred to mild 

* See Specifications for First-class Steel, page 38. 



24 American Steel and Wire Company 

steel. The objection to it for reinforced concrete is based largely upon the 
use of a poor quality of material. Another objection which has been raised is 
that before the elastic limit is reached, the stretch in the high steel may pro- 
duce an excessive cracking in the concrete in the lower portion of the beam, 
and thus expose the steel to corrosion. The mere fact that cracks are visible 
does not prove that they are dangerous, because the steel is always designed 
to take the whole of the tension. This point remains to be definitely settled, 
but Mr. Considere's and Professors Talbot's and Turneaure's tests indicate 
that there is no dangerous cracking even with high steel until the yield point 
of the steel is reached. This fact can be positively determined by cutting 
sections from reinforced concrete beams which have been strained nearly to 
the elastic limit, and testing them for corrosion by the methods employed by 
Prof. Charles L. Norton. (See page 427.) A yield point in steel of 30,000 
pounds per square inch corresponds to a stretch of 0.0010 of its length and a 
yield point of 50,000 to a stretch of 0.001G7. (See page 290.) 

A steel with a high modulus of elasticity would be particularly serviceable 
for reinforced concrete, because the higher the modulus of elasticity of a ma- 
terial, the less is the deformation under any given loading. Unfortunately, 
however, a high carbon steel has substantially the same modulus of elasticity 
(30,000,000 pounds per square inch) as ordinary merchant steel. 

The brittleness feared in high steel is less dangerous in reinforced con- 
crete than in any classes of structural steel work because the concrete protects 
it from shock, and also because smaller sections of steel are used in concrete 
beams than in steel beams, and the large and irregular shapes of the latter 
render them much more sensitive to irregular cooling during the process of 
their manufacture. 

It may be stated, then, if the stretching of high steel when pulled to its 
allowable working stress is proved not to form dangerous cracks in the con- 
crete, that high carbon steel, say, 0.56 per cent to 0.60 per cent carbon, of 
the quality used in the United States for making locomotive tires, is always 
better than mild steel for reinforced concrete, provided the steel is well melted 
and rolled, and is comparatively free from impurities, such as phosphorus. 
However, a high carbon steel, unless limited by chemical analysis, and made 
under careful inspection, is in danger of being more brittle than low carbon 
steel. Its use, therefore, should be limited strictly to work important enough 
to warrant the ordering of a special steel and the taking of sufficient trouble 
on the part of the purchaser to insure strict adherence to the specification. 
Under such circumstances, the use of high steel is attended with much economy. 
In other words, since manufacturers cannot always be depended upon to 
exactly follow specifications of this nature, it is necessary that an inspector be 
sent to the works, or else that the steel be purchased from a reliable dealer 
who has had it thus carefully tested. 



Concrete Reinforcement 25 

The specifications for first-class steel on page 38 are sufficiently explicit, 
so that steel which comes up to them can be safely used. A steel which can 
be employed with safety for all the locomotive and car wheels of the country 
certainly cannot be discarded as unsafe for concrete, provided similar precau- 
tions are taken in its purchase. 

From page 68, " Reinforced Concrete," by Buel & Hill: 

Grade of Steel The quality of steel used in reinforcing concrete should be 
as carefully specified as for an all-steel structure doing the 
same duty. Some engineers advocate the use of high steel, on account of its 
high elastic limit, which recent tests show gives a higher ultimate strength to 
the beam. The breaking load for beams having the proper amount of rein- 
forcement appears to be at about the elastic limit of the steel. In most cases, 
and certainly in structure subject to shock or impact, the writer considers it 
better and more conservative practice to use medium or mild structural steel, 
except for reinforcement for thermal and shrinkage stresses only, where high 
steel appears to be preferable. 



26 American Steel and Wire Company 



Protection of Steel or Iron from Corrosion 

Most tests which have been conducted of steel imbedded in concrete have 
resulted in positive proofs of the protection offered by the Portland cement 
concrete, not only from corrosion or rust, but from the most severe fire that is 
liable to occur. Of course the steel must be imbedded of sufficient depth in 
the concrete to obtain these results — from one to two inches being usually 
accepted as a safe distance from the surface. While these results are not as 
readily obtained with a cinder concrete, yet by being thoroughly wet and well 
mixed, they should be. 

Many engineers condemn cinder concrete owing to its extremely porous 
nature, thereby allowing the moisture and air to penetrate to the steel, which 
in a comparatively short time will rust it out entirely. In many instances the 
corrosion of steel in cinder concrete has been attributed to the sulphur con- 
tained in the cinders ; this, however, is not now accepted as the cause, but is 
due to the fact that it has not been mixed thoroughly and sufficiently wet. 

Cinders often contain oxide of iron, and when this is the case, and the 
mixture is not sufficiently wet to giye the steel a thorough coating with cement, 
it quickly corrodes any steel with which it comes in contact. 

The following pages, " Preservation of Iron in Concrete," reprinted from 
Chapter XII, "Reinforced Concrete," by Buel & Hill, contain some interest- 
ing tests on this subject : 

Preservation of Iron in Concrete It has generally been assumed that iron 

or steel embedded in concrete does not 
corrode, and many instances are cited of embedded steel being removed from 
concrete quite as clear and bright after a long period of exposure to the ele- 
ments as it was when first embedded. It should be noted, however, that an 
occasional instance is cited to show that under certain circumstances metal 
embedded in concrete will corrode. As the durability of concrete steel re- 
quires that the steel shall be permanently protected from corrosion, this ques- 
tion is an important one and it has received consideration from a number of 
experts. The commonly accepted theory accounting for the protection from 
rust of iron embedded in concrete has been recently stated by Prof. Spencer 
B. Newberry as follows : 

The rusting of iron consists in oxidation of the metal to the condition of 
hydrated oxide. It does not take place at ordinary temperatures in dry air or 
in moist air free from carbonic oxide. The combined action of moisture and 
carbonic acid is necessary. Ferrous carbonate is first formed ; this is at once 
oxidized to ferric oxide and the liberated carbon dioxide acts on a fresh 
portion of metal. Once started the corrosion proceeds rapidly, perhaps on 
account of galvanic action between the oxide and the metal. Water holding 
carbonic acid in solution soon, if free from oxygen, acts as an acid and rapidly 
attacks iron. In lime-water or soda solution the metal remains bright. The 
action of cement in preventing rust is now apparent. Portland cement con- 
tains about 63 per cent lime. By the action of water it is converted into a 



Concrete Reinforcement 27 



crystalline mass of hydrated calcium silicate and calcium hydrate. In hard- 
ening it rapidly absorbs carbonic acid and becomes coated on the surface 
with a film of carbonate, cement mortar thus acting as an efficient protector of 
iron and captures and imprisons every carbonic-acid molecule that threatens 
to attack the metal. The action is, therefore, not due to the exclusion of the 
air, and even though the concrete be porous, and not in contact with the metal 
at all points, it will still filter out and neutralize the acid and prevent its cor- 
rosive effect. 

The use of cement washes and plasters for the specific purpose of protect- 
ing iron and steel from rust is quite common and has extended over a long 
period of time. Cement paint is largely used by the railway companies of 
France to protect their metal bridges from corrosion. Two coats of liquid 
cement and sand are applied with leather brushes. After investigation and 
careful tests the engineers of the Boston Subway adopted Portland cement 
paint for the protection of the steel beams of that structure. Iron spirit-tanks 
for European distilleries are universally painted on the inside with Portland 
cement paint to prevent corrosion. In the United States it is a frequent 
practice to coat the inside of steel salt-pans, sulphate digesters, etc., with 
cement plaster to prevent corrosion. Regarding the damage from corrosion by 
the sulphur in the cinders of cinder concrete Prof. Newberry expresses himself 
as follows : 

The fear has sometimes been expressed that cinder concrete would prove 
injurious to iron on account of the sulphur contained in the cinders. The 
amount of this sulphur is, however, extremely small. Not finding any definite 
figures in this point, I determined the sulphur contained in an average sample 
of cinders from Pittsburg coal. The coal in its run state contains a rather high 
percentage of sulphur, about 1.5 per cent. The cinders proved to contain only 
0.61 per cent sulphur. This amount is quite insignificant, and even if all 
oxidized to sulphuric acid it would at once be taken up and neutralized in 
concrete by the cement present, and would by no possibility attack the iron. 

In connection with this statement it may be noted that in the demolition 
in 1903 of a tall steel-frame building in New York City, which was built in 1898 
and had practically all of its framework except the columns embedded in cinder 
concrete, the steel removed showed practically no rust which could be con- 
sidered as having developed after the metal was embedded. 

Tests of a reliable character, made to determine the efficiency of concrete 
in protecting embedded metal from corrosion, are comparatively few. The 
most important ones which have been published are those of Mr. Breuillie of 
France and those of Prof. Charles L. Norton of Boston, Mass. Mr. Breuillie 's 
tests were extended in character and the conclusions drawn from them by the 
experimenter were: (1) That the cement attacked the iron; (2) that water 
dissolved the composition which formed at the contact of the two materials ; 
(3) that the adhesion of the steel to the cement disappeared when water passed 
through the concrete for a certain time ; (4) that the weight of the iron salts 
which adhered to the steel and the normal adhesion between the steel and the 



28 American Steel and Wire Company 



concrete increased with time ; (5) in all cases the action of the cement on the 
iron prevented rust and removed the rust from metal which had been allowed 
to corrode before being embedded. 

The tests conducted by Prof. Charles L. Norton of the Massachusetts 
Institute of Technology, Boston, Mass., were of a somewhat different character 
from those of Mr. Breuillie. Briquettes or blocks were made of neat cement ; 
of 1 part cement and 3 parts sand; of 1 part cement and 5 parts broken 
stone, and of 1 part cement and 7 parts cinders. Portland cement was 
used, and was tested chemically and physically and found good. The 
cinders when washed down with a. hose-stream and dried tested alkaline, and 
analysis revealed very small amounts of sulphur. In each block there was 
embedded a ^-inch rod, a piece of soft sheet steel 6X1X232 inches, and a 
6 X 1-inch strip of expanded metal. These blocks were exposed as follows: 
one-quarter of them in sealed chests containing an atmosphere of steam, air, 
and carbon dioxide ; one-quarter in a similar chest with an atmosphere of air 
and carbon dioxide ; one-quarter in a chest with an atmosphere and steam, and 
one-quarter on a table in the open air of the testing-room. At the end of three 
weeks the blocks were carefully cut open, and the steel examined and compared 
with specimens which had laid unprotected in the corresponding chests and in 
the open air. 

The results of the examinations were as follows : The unprotected 
specimens consisted of rather more rust than steel. The specimens embedded 
in neat cement were perfectly protected. Of the remaining specimens hardly 
one had escaped serious corrosion. The location of the rust-spot was invariably 
coincident with either a rod in the concrete or a badly rusted cinder. In the 
more porous mixtures the steel was spotted with alternate bright and badly 
rusted areas, each clearly denned. In both the solid and the porous cinder 
concrete many rust-spots were found, except where the concrete had been 
mixed very wet, in which case the watery cement had coated nearly the whole 
of the steel, like a paint, and protected it. The following are Prof. Norton's 
conclusions from his tests . 

(1) Neat Portland cement, even in thin layers, is an effective preventive 
of rusting. 

(2) Concrete, to be effective in preventing rusting, must be dense and 
without voids and cracks. It should be mixed quite wet when applied to the 
metal. 

(3) The corrosion found in cinder concrete is mainly due to the iron oxide, 
or rust, in the cinders and not to the sulphur. 

(4) Cinder concrete, if free from voids and well rammed when wet, is about 
as effective as stone concrete in protecting steel. 

(5) It is of the utmost importance that the steel be clean when bedded in 
concrete. Scraping, pickling, a sand-blast, and lime should be used, if necessary, 
to have the metal clean when built into a wall. 

At first sight the conflicting testimony which had been quoted appears to 
have but little solid ground upon which the practicing engineer can base a 
decision as to the probable damage from rust of iron or steel embedded in 



Concrete Reinforcement 29 



concrete. A brief analysis will show, however, that this is not actually the case. 
In the first place there are many instances where steel embedded in concrete 
has shown no signs of rust upon removal. None of the evidence presented 
disputes this fact. Secondly, steel removed from concrete which contained 
cracks or voids has in many instances shown rust, always at the points where 
the cracks and voids were located. None of the evidence presented disputes 
this fact. Thirdly, the theory that the concrete covering filters out and renders 
innocuous the corrosive elements so completely as to protect the steel even 
where it is not in contact with the concrete is disputed by the results of Prof. 
Norton's tests. Fourthly, Prof. Norton's tests show that where the concrete is 
so closely in contact with the steel as to completely cover it with cement there 
is no corrosion. This fact is not disputed by any of the other evidence. 
Fifthly, Prof. Norton's tests show that wet concrete mixtures more certainly 
insure the close contact of the steel and concrete at all points than do dry 
mixtures. This fact is not disputed by any of the other evidence. Sixthly, 
Prof. Norton's contention that the steel should be perfectly cleaned before it is 
bedded in concrete is controverted by the tests of Mr. Breuille, which show that 
bedding in concrete will remove the rust from previously corroded steel. 
Seventhly, all the evidence presented indicates that the sulphur content of the 
cinders is not a serious element of danger in cinder concrete and that, other 
conditions being the same, cinder concrete and stone concrete are about equally 
efficient in preventing the rusting of embedded steel. The useful conclusion 
which the practicing engineer can draw from all this is that, so far as danger 
from subsequent rusting is concerned, he can confidently embed steel or Iron 
reinforcement in either cinder or stone concrete if he secures a close contact 
between the concrete and steel at all points, and if no cracks develop in the 
concrete to expose the metal to attack. 



30 American Steel and Wire Company 

Fire Protection 

The value of concrete as a fireproofing is apparently unquestionable, not 
alone from laboratory experiments, etc., but from fires which have actually 
occurred in buildings where this material has been employed. (See Fire Test 
Report on page 127.) 

The following from page 431 of Taylor & Thompson's volume, " Concrete, 
Plain and Reinforced," contains some very interesting results of both tests and 
actual fires : 

Numerous experimental tests* have been made showing the value of 
concrete as a fire-resisting material, but the best proof of its ability to resist the 
heat of a severe fire — such as is liable to occur in an office or factory building — 
lies in the fact that concrete has actually withstood very severe fires more 
successfully than have terra-cotta and various other so-called fireproof materials. 

The reinforced concrete factory of the Pacific Coast Borax Co., at Bayonne, 
N. J., passed through a severe fire in 1902. Still more recently, in 1904, 
occurred the conflagration at Baltimore in which many building materials 
utterly failed. 

Such practical tests, further confirmed by numerous experiments with test 
buildings of reinforced concrete, have proved that while in a severe fire, where 
the temperature ranges from 1600 degrees to 2000 degrees Fahr., the surface of 
the concrete may be injured to a depth of from ^ to ^ inch, the body of the 
concrete is unaffected, so that the only repairs required consist of a coating of 
plaster, and even this only in rare instances. 

Tests upon small briquettes of cement placed in a furnace indicate that the 
strength of cement is destroyed by a heat reaching a dull, red color, | but as 
stated below, in an actual fire, the injured material protects the rest of the 
concrete so that the danger is theoretical rather than real. 



Fire in Borax Factory The fire in the four-story reinforced concrete factory 

of the Pacific Coast Borax Company, | built entirely 
of concrete except the roof, utterly destroyed the contents of the building, the 
roof and the interior framework, but the walls and floors remained intact ex- 
cept in one place where an 18-ton tank fell through the plank roof and cracked 
some of the floor beams, and in one place on the outside of the wall where the 
surface of the concrete was slightly affected. The fire was so hot that brass and 
iron castings were melted to junk. A small annex, built of steel posts and girders, 
was completely wrecked, and the metal bent and twisted into a tangled mass. 

Baltimore Fire The effect of the fire upon the concrete in various buildings 
located in the center of the burned districts of Baltimore is 

*See References, Chapter XXIX. 

t Digest of Physical Tests, Volume I, page 217. 

t See page 463. 



Concrete Reinforcement 31 



best appreciated by an examination of the reports of experts upon the fire. 
Capt. John S. Sewell, in his report to the Chief of Engineers, U. S. A.,* in 
referring to the fire in one of the buildings built with reinforced concrete 
columns, beams, and arches, writes : 

It was surrounded by non-fireproof buildings, and was subjected to an 
extremely severe test, probably involving as high temperature as any that ex- 
isted anywhere. The concrete was made with broken granite as an aggregate. 
The arches of the roof and the ceiling of the upper story were cracked along 
the crown, but in my judgment very slight repairs would have restored any 
strength lost here. Cutting out a small section — say an inch wide — and 
caulking it full of good, strong cement mortar would have sufficed. The 
exposed corners of columns and girders were cracked and spalled, showing a 
tendency to round off to a curve of about 3 inches radius. In the upper 
stories, where the heat was intense, the concrete was calcined to a depth of 
from % X.o Y\ inch, but it showed no tendency to spall, except at exposed 
corners. On wide, flat surfaces, the calcined material was not more than 
yl inch thick, and showed no disposition to come off. In the lower stories, the 
concrete was absolutely unimpaired, though the contents of the building were 
all burned out. In my judgment, the entire concrete structure could have 
been repaired for not over 20 per cent to 25 per cent of its original cost. On 
March 10, 1 witnessed a loading test of this structure. One bay of the second 
floor, with a beam in the center, was loaded with nearly 300 pounds per square 
foot superimposed, witho\it a sign of distress, and with a deflection not 
exceeding }i inch. The floor was designed for a total working load of 150 
pounds per square foot. The sections next to the front and rear walls were 
cantilevers, and one of these was loaded with 150 pounds per square foot 
superimposed, without any sign of distress, or undue deflection. 

Captain Sewell concludes as a result of the examination of this and other 
buildings containing reinforced concrete construction : 

As the material is calcined and damaged to some extent by heat, enough 
surplus material should be provided to permit of a loss of, say, ^ inch all over 
exposed surfaces, if the structure is to be exposed to fire ; moreover, all ex- 
posed corners should be rounded to a radius of about 3 inches. This latter 
precaution would add much to the resistance of all materials used in masonry — 
whether bricks, stone, concrete or terra-cotta — if they are to be exposed to fire. 

Concrete Versus Terra-cotta Prof. Norton, in his report on the Baltimore 

fire to the Insurance Engineering Experiment 
Station,f says : 

Where concrete floor arches and concrete-steel construction received the 
full force of the fire it appears to have stood well, distinctly better than the 
terra-cotta. The reasons I believe are these : First, because the concrete and 
steel expand at sensibly the same rate, and hence when heated do not subject 
one another to stress, but terra-cotta usually expands about twice as fast with 
increase in temperature as steel, and hence the partitions and floor arches soon 
become too large to be contained by the steel members which under ordinary 
temperature properly enclose them. Under this condition the partition must 
buckle and the segmental arches must lift and break the bonds, crushing at 
the same time the lower surface member of the tiles. 



* Engineering News, March 24, 1904, page 27G. 
t Engineering News, June 2, 1904, page 529. 



32 American Steel and Wire Company 

When brick or terra-cotta are heated no chemical action occurs, but when 
concrete is carried up to about 1,000 degrees Fahr. its surface becomes decom- 
posed, dehydration occurs and water is driven off. This process takes a 
relatively great amount of heat. It would take about as much heat to drive 
the water out of this outer quarter inch of the concrete partition as it would to 
raise that quarter inch to 1,000 degrees Fahr. Now a second action begins. 
After dehydration the concrete is much improved as a non-conductor, and yet 
through this layer of non-conducting material must pass all the heat to dehy- 
drate and raise the temperature of the layers below, a process which cannot 
proceed with great speed. 



Cinder Versus Stone Concrete Prof. Norton compares the action of stone 

and cinder concrete in the Baltimore fire 
as follows: Little difference in the action of the fire on stone concrete and 
cinder concrete could be noted, and as I have earlier pointed out, the burning 
of the bits of coal in poor cinder concrete is often balanced by the splitting of 
the stones in the stone concrete. I have never been able to see that in the 
long run either stood fire better or worse than the other. However, owing 
to its density the stone concrete takes longer to heat through. 

Further experiments are required to determine the relative durability 
under extreme heat of concrete made with different kinds of broken stone. It 
seems probable, from the composition of the rock, that hard trap or gravel 
may be preferable to limestone, slate, or conglomerate as fire-resisting material. 



Thickness of Concrete Required The conclusion reached by Prof. Nortonf 
to Protect Metal from Fire from tests upon concrete arches is that 
™~ — — ^^— ^ wo mc j ies Q £ good concrete gives perfect 

assurance of safety in case of fire, even if the steel to be protected is in the 
form of I-beams. Rods of small dimensions can be more effectively coated, and 
it appears evident from the various tests and from practical experience in severe 
fires that 1 ^ inches ot concrete around steel rods is sufficient protection. The 
Pacific Borax Company's fire and other similar tests indicate that in slabs of 
reinforced concrete, ^2 inch to ^ inch affords ample protection. Secondary 
members, such as cross girders, or slabs of long span, should have a thickness 
of concrete outside of the steel varying from % inch to 1)4 inches. Although 
the slabs protected by only j4 inch of concrete, the latter may be softened by 
an extreme fire, and the metal exposed when it is struck by the stream from a 
hose, the metal in the majority of cases would still remain practically uninjured, 
and it is questionable economy to put an excess of material where there is so 
little probability of its being needed, and where a failure would merely produce 
local damage. 



Theory of Fire Protection 

Mr. Spencer B. Newberry, in an address delivered before the Associated 
Expanded Metal Companies, February 20, 1902,* gives the following explan- 
ation of the fire-proof qualities of Portland cement concrete: 

t Insurance Engineering, Dec, 1901, page 483. 
* Cement, May, 1902, page 95. 



Concrete Reinforcement 33 



The two principal sources from which cement concrete derives its capacity 
to resist fire and prevent its transference to steel are its combi?ied water and 
porosity. Portland cement takes up in hardening a variable amount of water, 
depending on surrounding conditions. In a dense briquette of neat cement 
the combined water may reach 12 per cent. A mixture of cement with 3 
parts sand will take up water to the amount of about 18 per cent of the cement 
contained. This water is chemically combined, and not given off at the boiling 
point. On heating, a part of the water goes up at about 500 degrees Fahr., but 
the dehydration is not complete until 900 degrees Fahr. is reached. This 
vaporization of water absorbs heat and keeps the mass for a long time at com- 
parative low temperature. A steel beam or column embedded in concrete is 
thus cooled by the volatilization of water in the surrounding cement. The 
principle is the same as in the use of crystalized alum in the casings of fire- 
proof safes ; natural hydraulic cement is largely used in safes for the same 
purpose. 

The porosity of concrete also offers great resistance to the passage of 
heat. Air is a poor conductor, and it is well known that an air space is a 
most efficient protection against conduction. Porous substances, such as 
asbestos, mineral wool, etc., are always used as heat-insulating material. 
For the some reason, cinder concrete, being highly porous, is a much better 
non-conductor than a dense concrete made of sand and gravel or stone, and 
has the added advantage of lightness. In a fire the outside of the concrete 
may reach a high temperature, but the- heat only slowly and imperfectly pene- 
trates the mass, and reaches the steel so gradually that it is carried off by the 
metal as fast as it is supplied. 



34 



American Steel and Wire Company 



Modulus or Coefficient of Elasticity 

Results of testing concrete for its modulus of elasticity for the same 
mixtures or proportions vary greatly. This is probably due to the exactness 
necessary in measuring the deformation of concrete. The modulus of elasti- 
city of steel varies from 28,000,000 pounds to 31,000,000 pounds per square 
inch ; 29,000,000 or 30,000,000 being the values usually accepted for steel. 
Those for concrete, of course, vary with the proportion or the mixtures. 

The following " Modulus of Elasticity," reprinted from Taylor & Thomp- 
son's, "Concrete, Plain and Reinforced," page 285, suggests the values for the 
modulus of elasticity of concrete : 

Modulus of Elasticity The modulus of elasticity of .steel varies from 
~~ 28,000,000 pounds per square inch to 31,000,000 

pounds per square inch ; 30,000,000 is customarily taken as an average value, 
and is the value which we have adopted. 

The modulus of elasticity of concrete, a very important factor in rein- 
forced concrete design, is considered in the preceding chapter, page 265. 
As there stated, it varies with the materials of which it is composed and with 
the proportions of these materials, also with the method of mixing and placing 
the concrete. 

As tentative values for use in reinforced design, the authors suggest the 
following moduli for concrete mixed of the wet consistency usually employed 
in beams : 



Broken stone or gravel concretes 



Cinder concrete 





Proportions 




r l:l^ 


3 




1:2 


4 


« 


1:2^ 


5 




1:3 


6 




1:5 


8 




1:2 


5 



Modulus of Elasticity 
Pounds per Square Inch 



4,000,000 
3,000,000 
2,500,000 
2,000,000 
1,500,000 
850,000 



It is probable that eventually these values will be found too low for dense, 
well-graded mixtures, which are gradually replacing those proportioned by rule 
of thumb methods. The authors have found a modulus of about 4,000,000 in 
12-inch concrete cubes mixed 1: 2 1-3: 4 2-3, the crushing strength of which 
was about 5,000 pounds per square inch at the end of two months. 

The higher the modulus of elasticity of the concrete, the lower should be 
the percentage of steel and the greater the depth of the beam for symmetrical 
design, that is, maintaining fixed relations of pull in steel to pressure in concrete. 

From tests of Prof. W. Kendrick Hatt* the modulus of elasticity in tension 
appears to be of similar value to the compressive modulus. Earlier experi- 
menters concluded that the modulus in tension is lower than in compression. 
A knowledge of the tensile modulus is, however, of less consequence 

♦Journal Association Engineering Societies, June, 1904, page 323. 



Concrete Reinforcement 35 



than the other because the tensile resistance of concrete is not usually 
considered. 

It is probable that there is an increase in the modulus of elasticity of 
concrete with age, but experiments by the author indicate that this is very slight. 

Recent tests,* contrary to former ideas, indicate that under different 
loadings there may be slight change in the modulus of elasticity of a given 
concrete until near to its crushing strength. This fact is of importance in 
fixing the distribution of stresses in the beam. 

Elongation or Stretch in Concrete The question of " Elongation or Stretch 

in Concrete " is dealt with in the suc- 
ceeding paragraph, reprinted from page 287 of Taylor & Thompson's volume. 

According to tests of Prof. Turneaure, already mentioned, concrete under 
a pull, as in the lower portion of a beam, will usually stretch 0.0001 to 0.0002 
of its length, that is 0.01 to 0.02 per cent, before showing minute cracks or 
" water-marks. " Cracks become readily noticeable at a stretching varying, 
in different specimens, from 0.0003 to 0.0010 of their length. The concrete 
in a reinforced beam stretches similarly to the concrete in a plain beam except 
that in the latter the beam breaks when the limit of stretch is reached, while if 
reinforced the pull is borne partly by the steel and partly by the concrete, and 
they both stretch together up to the point that cracks so minute at first as to 
be almost invisible occur in the concrete. 

" v The action of the reinforced concrete is shown in the deflection curve in 
Fig. 89. The inclination of this curve changes at about the same load that is 
required to break a similar beam or plain concrete. 

The diagram shows a typical result of Prof. Talbot's tests of the defor- 
mation of the concrete and the deformation of the steel, the deflection of the 
beam, and the various measured positions of the neutral axis during flexure. 
Among other conclusions, Prof. Talbot draws the following : 

1. The composite structure acts as a true combination of steel and con- 
crete in flexure during the first or preliminary stage, and this stage lasts until 
the steel is stressed to, say 3,000 pounds per square inch, and the lower 
surface of the concrete is elongated at about xo-J-5-5- of its length. 

2 During the second or readjustment stage there is a marked change in 
distribution of stresses, the neutral axis rises, the concrete loses part of its 
tensional valve, and tensile stresses formerly taken by the concrete are 
transferred to the steel. During this stage minute cracks probably exist, quite 
well distributed and not easily detected. 

3 In the third or straight-line stage the neutral axis remains nearly 
stationary in position and the concrete gradually loses more of its tensional 
value. Visible cracks appear and gradually grow larger, though no change in 
the character of the load-deformation diagram results. It would seem 
probable that at these cracks the stress in the steel is more than is indicated 
by the average deformation for the full gage length. 

*See Discussion on Concrete, by Sanford E. Thompson, International Eng. Congress, St. Louis, 1904. 



36 American Steel and Wire Company 



Prof. Talbot states that at the load when the curve changes character, 
which in the beam shown in the diagram is about 8,000 pounds total 
load — there are probably invisible cracks in the lower portion of the beam. 
This change in direction of the curve, indicating a suddenly increased load 
upon the steel, is strong proof of the loss in tensional resistance of the concrete. 
Prof. Turneaure, moreover, in his experiments, at loads somewhat beyond the 
point of change in direction, actually discovered these minute cracks. He 
tested his beams upside down, that is, the load was applied upward, and the 
minute cracks or water-marks were shown by hair lines on the wet surface of 
the concrete. Prof. Turneaure* says : 

It has been found that by testing the beams when somewhat moist, a 
crack is made visible when exceedingly small, it appearing first as a narrow, 
wet streak perhaps ^-inch wide and a little later as a dark hair-like crack. It 
was not necessary to search for the lines with a microscope, as under these 
conditions they were readily found. 

That the wet streak, called a " water-mark " hereafter, shows the presence 
of an actual crack was demonstrated last year by sawing out a strip of the 
concrete containing such a water-mark ; the strip fell apart at the water-mark. 

In the plain concrete no water-marks or cracks were observed before 
rupture. Comparing the observed and calculated elongations of the reinforced 
concrete with those for the plain concrete at rupture, it will be seen that the 
initial cracking in the former occurs at an elongation pratically the same as in 
the latter. 

The significance of these minute cracks is an open question. It has been 
supposed that concrete reinforced by steel will elongate about ten times as much 
before rupture as will plain concrete. These experiments show very clearly 
that rupture begins at about the same elongation in both cases. In the plain 
concrete total failure ensues at once ; in the reinforced concrete rupture occurs 
gradually, and many small cracks may develop so that the total elongation at 
final rupture will be greater than in the plain concrete. In other words, the 
steel develops the full extensibility of a non-homogeneous material that other- 
wise would have an extension corresponding to the weakest section. 

* Proceedings American Society for Testing Materials, 1904. 



Concrete Reinforcement 37 



Bonding Old and New Concrete 

Too much attention cannot be paid by constructors or contractors to the 
bonding of old and new concrete. In most instances sufficient care is not 
given to this in construction. The following from page 376 of " Concrete, 
Plain and Reinforced," Taylor & Thompson, should be carefully noted: 

In a foundation or other structure where the strain is chiefly compressive, 
the surface of the concrete laid on the previous day should be cleaned and 
wet, but no other precaution is necessary. Joints in walls or in other locations 
liable to tensile stress are coated with mortar, which should be richer in 
cement than the mortar in the concrete, proportions 1 : 2 being commonly 
used. 

Some engineers spread the cement dry upon the wetted surface of the 
old concrete, while others make it into a mortar ; the latter method is neces- 
sary in many cases to seal the joints between the top of the old concrete and 
the bottom of the raised forms. 

The adhesive strength of cement or concrete is much less than its 
cohesive strength, hence in building thin walls for a tank or other work which 
must be water-tight, the only sure method is to lay the structure as a monolith, 
that is, without joints. If the wall is to withstand water pressure and cannot be 
built as a monolith, both horizontal and vertical joints must be first thoroughly 
cleaned of all dirt and " laitance " or powdery scum, wet, and then covered 
with a very thin layer of either neat cement or 1: 1 mortar, according to the 
nature of the work. As an added precaution one or more square or V-shaped 
sticks of timber, say 4 or 6 inches on an edge, may be imbedded in the 
surface or placed vertically at the end of a section of the last mass of concrete 
laid each day. In some instances large stones have been partially imbedded 
in the mass at night for doweling the new work next day. 

In the New York Subway, work was commenced with no provision for 
bonding horizontal layers, but it was soon found that more or less seepage 
occurred, and in one case where a large arch was torn down, the division line 
between two days' work was distinctly seen. Accordingly, at the end of each 
day's concreting a tongue-and-grooved joint was formed by a piece of timber 
4 inches square partly imbedded in the top layer. This was removed before 
resuming work. 

Roughening the surface after ramming or before placing the new layer 
will aid in bonding the old and new concrete. 



38 American Steel and Wire Company 

Effect of Freezing 

The much discussed subject of the effect of freezing or frost upon 
Portland cement concrete seems to still be a question in the minds of many. 
This is possibly due, in some cases, to the confusion of natural and Portland 
cements. Most natural cements are completely ruined by freezing, while 
Portland cements seem uninjured. 

Numerous tests and investigations have been made in recent years, both 
in practical work and in laboratories ; the results being that the only per- 
manent injury is to the surface, which may scale off if frozen before setting, 
and that the hardening and setting is retarded. 

In practice the materials are often heated, which causes the cement to 
set more quickly ; or a limited amount of salt may be added to the water with 
apparently no injury to the concrete. 

The following reprinted from Chapter XIX, Taylor & Thompson's 
volume, "Concrete, Plain and Reinforced," is most interesting. 

Numerous experimental tests have been made, chiefly in the United 
States, where the effect of frost is a more serious question than in England, 
France or Germany, to determine the effect of freezing temperatures upon 
hydraulic cements. Although the conclusions of different experimenters are 
not in perfect accord, it is the generally accepted belief, corroborated by 
tests under the most practical conditions and by the appearance of concrete 
and mortar in masonry construction, that the ultimate effect of freezing upon 
Portland cement concrete and mortar is to produce only surface injury. 

In their practice and research the authors have never discovered a case, 
either in laboratory work or in practical construction, where Portland cement 
concrete or mortar laid with proper care has suffered more than surface disin- 
tegration from the action of frost. They do not wish to imply, however, that 
it is always expedient to lay Portland cement masonry in freezing weather, for 
the expense of laying is increased, and it is much more difficult to satisfactorily 
mix and place the materials. Mortar for brick and stone masonry freezes in 
the tubs and in the joints, while in laying concrete the surface freezes unless 
measures are taken to prevent it, and any dirt or " laitance " which rises to 
the surface of wet mixtures is hard to remove. It is a well-known fact that a 
thin crust about -^ inch thick is apt to scale off from granolithic or concrete 
pavements which have frozen, leaving a rough instead of a troweled wearing 
surface, and the effect upon concrete walls is often similar. It may be 
stated as a general rule that concrete work should, if possible, be avoided in 
freezing weather, although if circumstances warrant the added expense, with 
proper precaution and careful inspection mass concrete may be laid with Port- 
land cement at almost any temperature. 

Most natural cements, on the contrary, are seriously injured by frost, 
especially by alternate freezing and thawing, and while occasional cases are 
on record, especially in heavy stone masonry in which the weighted joints have 



Concrete Reinforcement 39 



thawed slowly, where natural cement mortar has been laid in freezing weather 
without serious results, numerous examples might be cited where even after 
several years the concrete or mortar was but slightly better than sand and 
gravel. Mr. Thompson has observed this result in natural cement mortar 
laid during the comparatively warm winter of North Carolina on days when 
the temperature was considerably above freezing at the time of laying, and 
also in the cold climate of Maine where the mortar froze as it left the trowel 
and did not thaw until spring. 

The settlement of the masonry when thawing is often a serious character- 
istic of natural cements. Stone masonry walls laid in freezing weather in 
natural cement mortar may settle as much as one-half inch in the height 
of a window jamb. 

Experiments upon natural cement mortars have not positively confirmed 
the judgment reached by nearly all engineers experienced in construction 
in freezing weather. Occasional tests are recorded in which such mortars, 
especially when subjected to a uniformly cold temperature and then suddenly 
thawed, have attained full strength, but these are insufficient to warrant the 
use of any except Portland cements when frost is likely to occur before the 
mortar is thoroughly dry. 

The prevention of injury from frost in certain cements may be due, at 
least in part, to the internal heat produced when setting. In the interior of a 
large mass, some cements, especially high-grade Portlands, attain a high tem- 
perature. (See page 130.) 



40 



American Steel and Wire Company 



Classification of Cements 

Chapter V, reprinted by permission from " Concrete, Plain and Rein- 
forced," by Taylor & Thompson : 

From an engineering standpoint, limes and cements may be classified as 
Portland cement. 
Natural cement. 
Puzzolan cement. 
Hydraulic lime. 
Common lime. 

Typical analyses of each are presented in the following table. The com- 
position of natural cement, even different samples of the same brand, is so 
extremely variable that their analyses cannot be regarded as characteristics of 
locality. 

Typical Analysis of Cements 





Portland 




Natural Cement 








Common Lime 




Cement 












c 
u 

E 

CD 

u 

c 
"o 

N 

N 

3 

28.95 


V 

E 








rt O 

— <D 

bfo x 

'J='c 

►J 


cti 

"o 

F c 

</. >- 

<U rt 

M 


American 


English 


French 


V 

J 
►J 






n 

V 

a S 

a o 


Western 
Louisville 3 


a 

E 
o 

(A 


10 
V) 

</} 
> 


c 
t/1 

S- 
<D 

"S. 
p. 
S3 

o 


c 

rt 

"3 2 

el c 

S3 


Silica Si O a 


21.31 


21.93 


18.38 


20.42 


25.48 


22 60 


26.5 


21.70 


1.03 


1.12 


Alumina Al 2 3 


6.89 


5.98 


} 15.20 


( 4.76 
I 3.40 


10.30 


8.90 


2 5 


11.40 


3.19 


fi.wj 


0.68 


Iron Oxide Fe 2 3 


2.53 


2.35 


7.44 


5.30 


1 5 


054 


0.66 




Calcium Oxide Ca O 


62.89 


62.92 


35.84 


46.61 


44 54 


52 69 


63.0 


50.29 


60.70 


97.02 


58.91 


Magnesian Oxide Mg O 


2.61 


1.10 


14.02 


12.00 


2 92 


1.15 


1 


2.96 


0.85 


0.68 


39.69 


Sulphuric Acid S 3 


1.34 


1.54 


0.93 


2.57 


2.61 


3 25 


0.5 


1.37 


0.60 






Loss on ignition 


1.39 


2.91 


3.73 


6.75 


3.68 


6.11 


5.0 


3.39 


12.20 






Other constituents 


0.75 




11.46 


3.74 


1.46 






30 


10 







1 W. F. Hillebrand, Society of Chemical Industry, 1902, Vol. XXI. 

2 W. F. Hillebrand, Journal American Chemical Society, 1903, 25, 1180. 

3 Clifford Richardson, Brickbuilder, 1897, page 229. 
4 Stanger & Blount, Mineral Industry, Vol. V., page 69. 

6 Candlot, Ciments et Chaux Hydrauliques, 1898, page 174. 

6 Le Chatelier, Annales des Mines, September and October, 1893, page 36. 

7 Report of the Board of U. S. Army Engineers on Steel Portland Cement, 1900, page 52. 

8 Candlot, Ciments et Chaux Hydrauliques, 1898, page 24. 

9 Rockland Rockport Lime Co. 
10 Western Lime and Cement Co. 



Concrete Reinforcement 41 

Portland Cement 

Portland cement is denned by Mr. Edwin C. Eckel of the U. S. Geolog- 
ical Survey as follows: "By the term Portland cement is to be understood 
the material obtained by finely pulverizing clinker produced by burning to 
semi-fusion an intimate artificial mixture of finely ground calcareous and 
argillaceous materials, this mixture consisting approximately of 3 parts of lime 
carbonate to 1 part of silica, alumina and iron oxide." 

The definition is often further limited by specifying that the finished 
product must contain at least 1.7 times as much lime, by weight, as of silica, 
alumina and iron oxide together. 

The only surely distinguishing test of Portland cement is its chemical 
analysis and its specific gravity. (See pages 64 and 65.) In the field it may 
often be recognized by its cold bluish gray color (see page 113), although the 
color of puzzolan and of some natural cement is so similar that this is by no 
means a positive indication. 

The term Natural Portland Cement arose from the discovery in Boulogne- 
sur-Mer, France, as early as 1816, of a natural rock of suitable composition 
for Portland cement. A similar discovery in Pennsylvania gave rise to the 
same term in America, but the manufacturers soon found it necessary to add 
to the cement rock a small percentage of purer limestone. Since the chemical 
composition of Portland cement, as defined above, is substantially uniform 
regardless of the materials from which it is made, in the United States the 
terms " natural " and " artificial " are meaningless. 

In France, cements intermediate between Roman and Portland are called 
"natural Portlands."* 

Sand Cement Sand or silica cement is a mechanical mixture of Portland 
cement with a pure, clean sand very finely ground together in 
a tube mill or similar machine. For the best grades the proportions of cement 
to sand are 1:1, although as lean a mixture as 1:6 has been made to compete 
with natural cements. The coarser particles in any Portland cement have 
little cementitious value, hence if a portion of the cement is replaced by inert 
matter and the whole ground extremely fine, its advocates maintain that the 
product is scarcely inferior to the unadulterated article. As made in the 
United States, the mixture is ground so fine that 95 per cent of it will pass 
through a sieve having 200 meshes to the linear inch, and all of the 5 per cent 
residuum is said to be sand. In other words, all of the cement passes a No. 
200 sieve. 

*Candlot's Ciments et Chaux Hydrauliques, 1898, page 164. 



42 American Steel and Wire Company 



Natural Cement 

Natural cement is "made by calcining natural rock at a heat below 
incipient fusion, and grinding the product to powder."* Natural cement con- 
tains a larger proportion of clay than hydraulic lime, and is consequently more 
strongly hydraulic. Its composition is extremely variable on account of the 
difference in the rock used in manufacture. 

Natural cements in the United States in numerous instances bear the 
names of localities where first manufactured. For example, Rosendale cement, 
a term heard in New York and New England more frequently than natural 
cement, was originally manufactured in Rosendale, Ulster County, N. Y. 
Louisville cement first came from Louisville, Ky. The James River, Milwau- 
kee, Utica and Akron are other natural cements named for localities. 

The United States produces a few brands of "Improved Natural Hydraulic 
Cement," intermediate in quality between natural and Portland, by mixing 
inferior Portland cement with natural cement clinker. 

In England the best known natural cement is called Roman cement. 
Occasionally one hears the term Parker's cement, so called from the name of 
the discoverer in England. 

Le Chatelier's Classification of Natural Cements 

In France there are several classes of natural cement. Mr. H. Le 
Chatelierf classifies natural cements as those obtained "by the heating of 
limestone less rich in lime than the limestone for hydraulic lime. They may- 
be divided into three classes : 

Quick-setting cements, such as Vassy and Roman (Ciments a prise 
rapide, Vassy, romain); 

Slow-setting cements (Ciments a prise demi-lente) ; 

Grappiers cements (Ciments de grappiers). 

Vassy Cements are obtained by the heating of limestone containing much 
clay, at a very low temperature, just sufficient to decarbonate 
the lime. They are characterized by a very rapid set, followed afterwards by an 
extremely slow hardening, much slower than that of Portland cements. 

They differ from Portland cements by containing a much higher percentage 
of sulphuric acid, which appears to be one of their essential elements, and a 
much lower percentage of lime. 

Slow-setting Cements by the high temperature of calcination, approach 

Portland cements, but the natural limestones never 
possess the homogeneity of artificial mixtures, so that it is impossible to avoid 
in these cements the presence of a large quantity of free lime. The compo- 
sition of these products varies from that of the Vassy cements to that of the 
real Portlands. 

♦Professional Papers, No. 28, U. S. Army Engineers, page 33. 
tProcedes d'Essai des Materiaux Hydrauliaues, Annales des Mines, 1893. 



Concrete Reinforcement 43 



" Grappiers Cements are obtained by the grinding of particles which have 

escaped disintegration in the manufacture of hydraulic 
limes. These grappiers are a mixture of four distinct materials, two of which, 
completely inert, are unburned limestone and the clinkers formed by contact 
with the siliceous walls of furnaces, and two of which, strongly hydraulic, are 
unslacked lime and true slow-setting cement. It is necessary that the latter 
should predominate in the grappiers for their grinding to give a useful product. 
The grappier of cement is obtained regularly only by the heating of a lime- 
stone but slightly aluminous and containing about three equivalents of car- 
bonate of lime for one of silica ; its production necessitates a heating at high 
temperature. 

These grappiers cements are even more apt to contain free lime than 
the natural cements of slow set which are obtained by the heating of limestone 
containing much more alumina. Because of their constitution also the grap- 
piers cements may vary greatly in composition since they are produced by the 
grinding of a mixture of grains of cement and of various inert materials. The 
cement grains have very nearly the composition of tricalcium silicate (Si0 2 
3CaO)." 

Puzzolan or Sla£ Cement 

Puzzolan cement is the product resulting from mixing and grinding 
together in definite proportions slaked lime and granulated blast furnace slag 
or natural puzzolanic matter (such as puzzolan, santorin earth, or trass 
obtained from volcanic tufa). 

The ancient Roman cements belonged to the class of Puzzolans. They 

were made by mechanically mixing slaked lime with natural puzzolana formed 

from the fusion of natural rock found in the volcanic regions of Italy. In 

Germany, trass, a volcanic product related to Puzzolan, has been used with 

ime in the manufacture of cements. 

Blast furnace slag is essentially an artificial puzzolana, formed by the 
combustion in a blast furnace, and the puzzolan or slag cements of the United 
States are ground mixtures of granulated blast furnace slag, of special com- 
position, and slaked lime. 

A Board of Engineers officers, U. S. A., presented in 1901 the following 
conclusion, * based undoubtedly on the exhaustive studies upon the subject 
made by a previous board | having the same chairman, Major W. L. Marshall: 

This term (slag or Puzzolan cement) is applied to cement made by 
intimately mixing by grinding together granulated blast furnace slag of a 
certain quality and slaked lime, without calcination subsequent to the mixing. 
This is the only cement of the Puzzolan class to be found in our markets 
(often branded Portland), and as true Portland cement is now made having 
slag for its hydraulic base, the term " slag cement " should be dropped and 
the generic term Puzzolan be used in advertisements and specifications for 
such cements. 

* Professional Papers, No. 28, page 28. 

t Report of the Board of U. S. Army Engineers on Steel Portland Cement, 1900, page 52. 



44 American Steel and Wire Company 



Puzzolan cement made from slag is characterized physically by its light 
lilac color ; the absence of grit attending fine grinding and the extreme sub- 
division of its slaked lime element ; its low specific gravity (2.6 to 2.8) com- 
pared with Portland (3 to 3 . 5) ; and by the intense bluish green color in the 
fresh fracture after long submersion in water, due to the presence of sulphides, 
which color fades after exposure to dry air. 

The oxidation of sulphides in dry air is destructive of Puzzolan cement 
mortars and concretes so exposed. Puzzolan is usually very finely ground, 
and when not treated with soda sets more slowly than Portland. It stands 
storage well, but cements treated with soda to quicken setting become again 
very slow setting, from the carbonization of the soda (as well as the lime) 
element after long storage. 

Puzzolan cement properly made contains no free or anhydrous lime, does 
not warp or swell, but is liable to fail from cracking and shrinkage (at the 
surface only) in dry air. 

Mortars and concretes made from Puzzolan approximate in tensile strength 
similar mixtures of Portland cement, but their resistance to crushing is less, 
the ratio of crushing to tensile strength being about 6 to 7 to 1 for Puzzolan, 
and 9 to 11 to 1 for Portland. On account of its extreme fine grinding 
Puzzolan often gives nearly as great tensile strength in 3 to 1 mixture as neat. 

Puzzolan permanently assimilates but little water compared with Port- 
land, its lime being already hydrated. It should be used in comparatively dry 
mixtures well rammed, but while requiring little water for chemical reactions, 
it requires for permanency in the air constant or continuous moisture. 

Puzzolanic material has been suggested by Dr. Michaelis, of Germany, 
and Mr. R. Feret, of France (see Chapter XVIII), as a valuable addition to 
Portland cement designed for use in sea water. 

Hydraulic Lime 

The hydraulic properties of a lime — its ability to harden under water — 
are due to the presence of clay, or, more correctly, to the silica contained in 
the clay. Hydraulic lime is still used to quite an extent in Europe, especially 
in France, as a substitute for hydraulic cement. The celebrated lime-of-Teil 
of France is a hydraulic lime. 

Mr. Edwin C. Eckel states * that " theoretically the proper composition 
for a hydraulic limestone should be calcium carbonate 86.8 per cent, silica 
13.2 per cent. The hydraulic limestones in actual use, however, usually carry 
a much higher silica percentage, reaching at times to 25 per cent; while 
alumina and iron are commonly present in quantities which may be as high as 
6 per cent. The lime content of the limestones commonly used varies from 
55 per cent to 65 per cent." 

Although the chemical composition of hydraulic lime is similar to Port- 
land cement, its specific gravity is much lower, lying between 2.5 and 2.8.f 

* American Geologist, March, 1902, page 52. 
tCandlot's Ciments et Chaux Hydraulique, 1898, page 26. 



Concrete Reinforcement 45 



In the manufacture of hydraulic lime the limestone of the required com- 
position is burned, generally in continuous kilns, and then sufficient water is 
added to slake the free lime produced so as to form a powder without crushing. 

Common Lime 

The commercial lime of the United States is "quicklime," which is chiefly 
calcium oxide (CaO). 

Lime is now manufactured by a continuous process. Limestone of a 
rather soft texture, so as to be free as possible from silica, iron and alumina, 
is charged into the top of the kiln which may be, say, 40 feet high by 10 feet 
in diameter. The fuel is introduced into combustion chambers near the foot 
of the shaft, and the finished product is drawn out from time to time through 
another opening in the bottom of the shaft. The temperature of calcination 
may range from 1,400 degrees Fahrenheit (760 degrees Centigrade) to, at times, 
2,000 degrees Fahrenheit (1,090 degrees Centrigrade). The product (see 
analysis, page 47), in ordinary lime of the best quality, is nearly pure calcium 
oxide (CaO). Upon the addition of water the lime slakes, forming calcium 
hydrate (CaH 2 2 ), and, with the continued addition of water increases in bulk 
to twice or three times the original loose and dry volume of the lump lime as 
measured in the cask. In this plastic condition it is termed by plasterers 
" putty " or " paste." 

The setting of lime mortar is the result of three distinct processes which, 
however, may all go on more or less simultaneously. First, it dries out and 
becomes firm. Second, during this operation, the calcic hydrate, which is in 
solution in the water of which the mortar is made, crystalizes and binds the 
mass together. Hydrate of lime is soluble in 831 parts of water at 78 degrees 
Fahrenheit; in 759 parts at 32 degrees and in 1136 parts at 140 degrees. 
Third, as the per cent of water in the mortar is reduced and reaches five per 
cent, carbonic acid begins to be absorbed from the atmosphere. If the mortar 
contains more than five per cent this absorption does not go on. While the 
mortar contains as much as 0.7 per cent the absorption continues. The 
resulting carbonate probably unites with the hydrate of lime to form a sub- 
carbonate, which causes the mortar to attain a harder set, and this may finally 
be converted to carbonate. The mere drying out of mortar, our tests have 
shown, is sufficient to enable it to resist the pressure of masonry, while further 
hardening furnishes the necessary bond.* 

Magnesian Limes evolve less heat when slaking, expand less, and set more rap- 
idly than pure lime. A typical analysis is given on page 47. 

Hydrated Lime is a powdered slaked lime (calcium hydrate). It is manu- 
factured by treating finely ground common lump lime with 
water of a certain temperature, and then cooling and screening it through a 
very fine screen. 

*The authors are indebted to Mr. Clifford Richardson for this paragraph. 



46 American Steel and Wire Company 



Finishing Surfaces of Reinforced Concrete 

Objections are often heard as to the unsightly appearance of concrete 
buildings wnen finished. With a little care concrete structures may be made 
as beautiful to the eye as buildings built of any other material. 

The following chapter, XVII, reprinted from Buel & Hill's volume, 
" Reinforced Concrete," will be found most interesting on this subject, dealing 
with the numerous finishes which may be applied at very little cost. 

Chapter XVII 

Facing and Finishing Exposed Concrete Surfaces 

The difficulty of securing an even-grained surface of uniform color on 
concrete work is one of the most annoying which builders of such work have 
to overcome. Concrete work is subject to various sorts of surface imperfection, 
but the two most common imperfections are roughness or irregular surface 
texture and variability of color or discoloration. Either of these imperfections 
is capable of disfiguring an otherwise sightly structure, and the task of avoid- 
ing them is one which warrants serious attention from those undertaking work 
in reinforced concrete. Unfortunately practice has not settled upon a solution 
of the problem, hence its consideration here is rather a record of experience 
than a set of instructions which can be followed with the certainty that suc- 
cessful results will ensue. 

Causes of Roughness There are several conditions which may result in a 
and Discoloration concrete surface of uneven texture and with mechani- 
cal roughnesses, such as projections, bulges, ridges, 
pits, bubble-holes and scales. One of these is imperfections in the molds. 
The use of rough lagging of uneven thickness and with open cracks and allow- 
ing the forms to become distorted and warped are certain to leave their impress 
upon the plastic concrete in the form of ridges, tongues and bulges. Failure 
to pack the concrete filling tightly and evenly against the mold will result in 
rough places. Lack of homogeneity in the concrete is another prolific cause 
of variation in the surface texture of concrete work. This lack of homogeneity 
may result from failure to mix the concrete materials thoroughly and evenly 
in the first place, or the segregation of the coarse and fine parts of the mixture 
during its deposition and ramming into place. In both cases the result is a 
material of alternate coarse and fine texture. Dirt or cement adhering to the 
molds will leave pits in the concrete surface, and the pulling away of the 
concrete in spots when it adheres to the molds when they are removed will 
cause similar roughness. 

Variations in the color of concrete surfaces probably result from a variety 
of causes. Some of these are obvious and others are difficult to determine 
with any exactness. Roughness or uneven surface texture is a common cause 
of variation in color, since the alternate rough and smooth parts weather 



Concrete Reinforcement 47 



differently and collect and hold dirt and soot in different degrees. Another 
cause of variation in color is the use of different cements in adjacent parts of 
the surface work. No two cements are of exactly the same shade of color, 
and the concrete made of them partakes of this variation. In a similar manner 
sand of different shades of color or of different degrees of cleanliness will cause 
a cloudy and streaky appearance in concrete. Dirt adhering to the molds will 
frequently stain the adjacent concrete surface. 

Even when the smoothness of the surface is satisfactory, however, and 
when there is no criticism possible as to the kind and quality of the aggregates, 
their deposition and the cleanliness with which the work is done, concrete 
surfaces frequently vary in color and have a cloudy light and dark appearance. 
In many cases there seems to be good reason for attributing this to the leach- 
ing out of lime, compounds and their disposition in the form of an efflorescence 
on the concrete surface. The extent of this efflorescence varies ; at times the 
deposit is so thin as merely to give a lighter shade to the places where it 
appears, but it will often form an encrustation of considerable body and thick- 
ness which may be readily scraped off as a white or yellowish-white powder. 
The nature of this discoloration and the preventive and remedial treatments 
which have been practiced in its cure are discussed more fully in a succeeding 
paragraph. 

Construction of Forms Very slight imperfections in the face of the forms 

against which the concrete is molded are sufficient 
to leave an unsightly impression on the plastic mixture when it hardens. Even 
the grain of smoothly dressed timber will show on the surface of concrete 
which has been deposited with a mortar facing. It is very difficult to construct 
forms so that they will not leave slight impressions of this character, and it is 
generally better not to attempt the task in any but exceptional instances. In 
these a straight-grained, smoothly dressed timber, with its pores filled with 
soap or paraffine well rubbed in, or a rougher timber covered with sheet metal, 
can be used. Generally speaking, all has been done that is practicable so far 
as the forms are concerned when the face-lagging is kept true to surface and 
has close-fitting joints. Grain-marks and similar minor impressions of the 
forms can usually be eliminated by rubbing the surface or floating it with 
grout, at less cost, than by attempting to perfect the molds beyond a reason- 
able measure. In fact many engineers experienced in concrete work prefer 
not to attempt to secure particularly perfect finish in the forms, but to dress 
the entire surface by some style of tooling or rubbing process after the forms 
have been removed. The most apparent imperfection in concrete surfaces is 
usually the joint-marks of the lagging-boards. These may be due either to 
slight differences in the thickness of adjoining boards or to open joints. The 
remedy for the first cause is obvious, but it is not so easy to insure smooth, 



48 American Steel and Wire Company 




tight joints and keep them smooth and tight when the boards swell from the 
moisture absorbed from the wet concrete. One of the most successful forms 
of joint is that shown by the sketch figure 78. In this con- 
struction the wedge edge presses into the edge of the adjoining 
board without distorting or bulging the lagging. Pointing the 
joints with hard soap or putty, packing them with oakum and 
covering them with pasted strips of cloth, are other means which 
have been practiced for preventing joint-marks on the concrete. 
A method of eliminating grain-marks, which was used with success 
in constructing piers of the Frazer River bridge in British 
Figure 78 Columbia, consisted in covering the tightly laid matched lagging 
with gloss oil and then blowing sand into the oil with hand-bellows. 

Mortar or Grout Facing One of the most frequently employed means for 

securing a smooth surface finish on concrete is to 
use a mortar or grout facing. This facing differs from plastering in being laid 
on as the concrete is deposited, thus forming a single piece with it. The 
thickness of mortar facing employed in practice varies from ^ to 3 inches, but 
the usual practice is to make it 1 or 1)4 inches thick. A facing as thick as 3 
inches is rather unnecessary waste of mortar, while one which is much less than 
1 inch thick is likely to be pierced by the stones in the concrete unless great 
care is taken in ramming the concrete filling behind the mortar facing. A mortar 
or grout facing shows the impress of small roughnesses on the mold more readily 
than does concrete, and particular care is necessary to secure a smooth surface 
in the mold when the mortar facing is adopted. The composition of the facing 
mortar is usually specified as 1 part of Portland cement to 2 or 3 parts of sand. 
These ingredients are mixed rather wet, since the paste must completely fill 
the facing-mold, but care must be had not to have so thin a paste that the 
stones from the concrete behind will be pushed through it during the subse- 
quent filling and ramming. 

The following method of placing mortar facing is practiced by the Illinois 
Central R. R. and has gained wide adoption during the last few years. A sheet- 
iron plate 6 to 8 inches wide and about 6 feet long has riveted across it on one 
side lj4 inch angles spaced about 2 feet apart. One edge of this plate is 
provided with handles. This device is employed as a mold for the facing and 
is operated in the following manner : The plate is set up against the face of 
the form with its angle-ribs close against the timber and its handles upward. 
In this position of the plate there is between it and the form an open slot 1^ 
inches wide. This slot is filled with mortar which is tamped thoroughly, and 
immediately afterwards the concrete backing is deposited behind the plate. 
When this has been done the plate is withdrawn by the handles and the backing 
and facing are rammed together to a close bond. The mortar facing is mixed 
in small batches as it is needed, and no delay is permitted in placing the 



Concrete Reinforcement 49 



concrete backing, the essential principle and purpose of the method being to 
secure as nearly as is possible the simultaneous construction of the backing of 
concrete and its facing of mortar. 

Figure 70 shows an excellent form of surface mold of the type just 
described. By varying the size of the angle-ribs any desired thickness of fac- 
ing can be constructed, and the flare of the top edge facilitates the placing of 
the mortar, which is usually done with shovels. In lieu of a steel plate, use 
is sometimes made of a board provided with furring-strips on one side. This 
is a more unwieldly device than the one illustrated, and it is objectionable 
because of the large crevice left upon withdrawal into which the mortar facing 
is likely to slough and which is less easily closed and bonded by the final 
ramming. In constructing mortar facing with either iron or board molds per- 
fect success is secured only at the expense of great care. The mortar must 
be mixed in small batches and only as needed, and it must be thoroughly 
rammed and churned into the facing-mold. The concrete backing must be 
deposited behind the mold without delay and firmly rammed against it, and 
finally the ramming together of the facing and backing must be thorough. 

The following method of applying grout facing was employed with success 
in constructing the Atlantic Avenue subway for the Long Island R. R. in 
Brooklyn, N. Y. The concrete was deposited in 6 or 8-inch layers, and after 
ramming, the concrete at the face was pushed back from the form about 1 inch 
with an ordinary gardener's spade and a thick grout of 1 part cement and 
2 parts sand w 7 as poured into the space. The forms used were tongued and 
grooved yellow pine painted with paraffine paint. In this work a good sur- 
face was invariably secured when the men did their work faithfully, but any 
carelessness on their part evidenced itself in a rough spot when the forms were 
removed. As an indication of the susceptibility of mortar facing in taking 
impressions from the forms, it may be noted that even with the dressed and 
paraffined lagging the grain of the wood was shown perfectly on the mortar 
facing. 

Finishing Mortar Facing When mortar or grout facing is employed as 

described in the preceding paragraphs the 
slightest imperfections in the grain of smoothly dressed wood is clearly im- 
pressed on the plastic material. There will also be occasional rough spots, 
pittings or bubble-holes even with the most careful construction. To get rid 
of these some method of surface finishing must be resorted to. A number of 
methods have been practiced. In recent concrete culvert work on the New 
York Central & Hudson River R. R. an excellent surface finish was obtained 
by the following procedure : The forms of 2-inch dressed and matched pine, 
after being put in place, were painted with a coat of thin soft soap, then as the 
layers of concrete were brought up, the face was drawn back with a square- 
pointed shovel, the edges of which had been hammered flat. Mortar in the 
proportion of 1 part cement to 2 parts sand, mixed rather wet, was then poured 



50 American Steel and Wire Company 



in along the form and the layer rammed against it. Hard soap was used to 
fill openings left by points of the lagging. When the forms were removed and 
white the concrete was yet "green," the surface was carefully rubbed with a 
circular motion, w r ith pieces of white firebrick or briquettes of 1 cement to 1 
sand, made in molds about the size of a building brick, handles being pressed 
in while soft. The surface was then dampened and painted with a coat of 
grout of 1 cement to 1 sifted sand, and this was closely followed by a final 
rubbing with a circular movement, using a wooden float. All edges were 
rounded with a Crafts edger, or with wood fillet, and the coping joints were 
struck with Crafts jointer. 

In the specifications for concrete presented by the special committee of 
the Engineering and Maintenance of Way Association the following require- 
ment for finishing was adopted : 

After the forms are removed, any small cavities or openings in the concrete 
shall be neatly filled with mortar if necessary. Any ridges due to cracks or 
joints in the lumber shall be rubbed down ; the entire face shall then be washed 
with a thin grout of the consistency of whitewash, mixed in the proportion of 
1 part of cement to 2 parts of sand. The wash should be applied with a brush. 

In the extensive concrete construction of the Aurora, Elgin & Chicago 
R. R. the exposed surfaces were all finished according to the following speci- 
fications : 

All walls when finished must present a smooth, uniform surface of cement 
mortar, and all disfigurements must be effaced, and if there are any open, 
porous places, they must be neatly filled with mortar of 1 cement and 2 sand, 
well rubbed in, which finishing must be done immediately upon the removal 
of the forms. Compensation for all labor and material required in such finish- 
ing, including the mortar facing when required, with the finishing of bridge 
seats and other parts, is included in the price per cubic yard for concrete work. 

Mr. Edwin Thacher, in his general specifications for concrete-steel, requires 
the following surface finish : 

For plain, flat surfaces, the concrete may be rammed directly against the 
molds, and, after the molds have been removed, all exposed surfaces shall be 
floated to a smooth finish with semi-liquid mortar, composed of 1 part cement 
and 2 parts of fine, sharp sand, care being taken that no body of mortar is left 
on the face, sufficient only being used to fill the pores and give a smooth finish. 

A very effective finish is obtained by etching the mortar facing with acid. 
The method consists of using a facing mortar composed of Portland cement 
and finely crushed stone, the kind of stone depending upon the appearance 
desired. Thus any shade of red or gray granite, sandstone, etc., can be 
obtained, and special effects can be obtained by the use of sand, pigments, 
etc., in the mixture. This mortar is composed of about 1 part Portland cement 
to 2 or 3 parts of the finely crushed stone. The exposed surfaces are then 
treated by chemical or mechanical means to remove the cement matrix at the 



Concrete Reinforcement 51 



face, leaving the granular particles of stone partly exposed. In general this 
is done by washing the surface with a weak acid solution, then w r ith clean water, 
and finally with an alkaline solution to neutralize any effects of the acid. In 
the finished work it is difficult to detect that the material is not natural stone, 
except by close inspection. The stone is crushed to pass through a sieve of 
10 to 30 meshes per square inch according to the character of finish desired, 
and enough water is used to make a soft plastic mixture. 

Plastering Plastering as a method of finishing concrete surfaces deserves 
mention for the purpose alone of calling a warning against its 
adoption. It is practically impossible to apply mortar in thin layers to a 
concrete surface and make it adhere for any length of time, and when it once 
begins to scale off the result is a surface many times worse in looks than the 
unfinished concrete that it was intended to render more sightly. 

Pebble Dash Facing An effective surface finish for certain classes of 

concrete w T ork can be secured by using large rounded 
pebbles in place of the usual aggregate for the surface layer of concrete, and 
then, w r hile the concrete is soft, removing the mortar between the pebbles by 
wire brushing until approximately half the pebbles are exposed. The follow- 
ing specification for this style of facing was employed in constructing a small 
concrete road-bridge in the National Park at Washington, D. C. : 

The concrete, which will be in the exterior faces of the bridge and the 
parapet walls for a thickness of 18 inches, will be made of gravel and rounded 
stone varying in the concrete below the belting course between 1^ and 2 
inches in their smallest diameters. This gravel will be mixed in the concrete 
as aggregate instead of broken stone. The mixture will consist of 1 part 
Portland cement, 2 parts sand, and 5 parts of aggregate. The parapet walls 
will be made in a similar manner, with the aggregate composed of gravel not 
exceeding 1 inch in its smallest diameter. When the forms are removed the 
cement and sand must be brushed from around the face of the gravel with 
steel brushes, leaving approximately half of the gravel exposed. 

In this work it was found by test that at the age of 12 hours the concrete 
was not sufficiently set to hold the pebbles from being torn out by the brushing, 
and that at the age of 36 hours it was too hard to permit the brushing to 
remove a sufficient depth of mortar without undue labor. At 24 hours' age the 
brushing proved most successful. 

Tooled Surfaces A method of finishing concrete surfaces which is preferred 
by many experienced engineers is to dress the concrete 
after it has hardened by means of hammers or pointed chisels. The process is 
exactly analogous to stone dressing, and any of the forms of finish employed 
for cut stone can be employed equally well for concrete. In connection with 
tooled surfaces it is common to mold the concrete to represent ashlar masonry 
by means of horizontal and vertical V-shaped depressions formed as shown by 
figure 80. This style of finish has been extensively employed by Mr. E. L. 
Ransome, who gives the following directions for securing it: In imitating 



American Steel and Wire Company 



rough-dressed work the mold is removed from the concrete while it is yet 
tender, and with small light picks the face is picked over with great rapidity, 
an ordinary workman finishing about 1,000 square feet per day. For imitations 
of finer tooled work the concrete should be left to harden longer before being 
spalled or cut, and the work should be done with a chisel. Most natural stone 
and especially granite makes excellent material for the face, but ordinary 
gravel will do. Whatever is used, let it be uniform in color and of even grade. 
When a very fine and close imitation of a natural stone is required take the 
same stone, crush it and mix it with cement colored to correspond. The finer 
the stone is crushed the nearer the resemblance will be upon close inspection ; 
but for fine work it is generally sufficient to reduce the stone to the size of 
buckshot or fine gravel. 

Masonry Facing A facing of masonry is often employed on reinforced 
concrete arch bridges, and is a very satisfactory solution 
of the problem of surface finish for such structures. Masonry facing may be 
of any style of stonework which is used for true masonry arches, and coursed 
ashlar, random rubble, and boulder masonry facings have all been employed. 
Exactly the same care should be exercised in selecting stones and laying them 
up into arch ring and wall, cornice and parapet, as if the structure were 
entirely of masonry. Beyond this the most important feature to be observed 
is close bonding of the masonry facing to the concrete backing. To insure 
this there should be a liberal use of stretchers reaching well into the backing, 
and these can be supplemented with metal cramps to the advantage of the 
work in many instances. For facing the arch ring the stones should be cut to 
true voussoir shape, and laid quite as perfectly as if they were a part of a true 
voussoir arch ring. The soffit of the arch ring is not stone-faced. In place 
of stone a brick facing may be employed. 

The following specifications for stone and brick facing, which were pre- 
pared by Mr. Edwin Thacher, M. Am. Soc. C. E., to control work conducted 
by him, give a fair idea of the requirements of high-class work of this character : 

Stone Facing If stone facing is used, the ring stones, cornices, and faces of 
" — — — spandrels, piers and abutments shall be of an improved 
quality of stone. The stone must be of a compact texture, free from loose 
seams, flaws, discolorations, or imperfections of any kind, and of such a 
character as will stand the action of the weather. The spandrel walls will be 
backed with concrete, or rubble masonry, to the thickness required, The stone 
facing shall in all cases be securely bonded or clamped to the backing. All 
stone shall be rock-faced with the exception of cornices and string courses, 
which shall be sawed or bush-hammered. The ring stones shall be dressed to 
true radial lines, and laid in Portland cement mortar, with ^-inch joints. All 
other stones shall be dressed to true beds and vertical joints. No joint shall 
exceed ^ inch in thickness and shall be laid to break joints at least 9 inches 
with the course below. All joints shall be cleaned, wet, and neatly pointed. 
The faces of the walls shall be laid in true lines, and to the dimensions given 
on plans, and the corners shall have a chisel draft 1 inch wide carried up to 



Concrete Reinforcement 53 

the springing lines of the arch, or string course. All cornices, moldings, 
capitals, keystones, brackets, etc., shall be built into the work in the proper 
positions and shall be of the forms and dimensions shown on plans. 

Brick Facing with The arch rings, cornices, string courses and quoins shall 
Concrete Trimmings be concrete-faced, as described above, the arch rings and 

quoins being marked and beveled to represent masonry. 
The piers, abutments and spandrels shall be faced with vitrified brick, as shown 
on plans. The brick facing shall be plain below the springing lines of the arches 
and rock-faced above these lines. All rock-faced brick shall be chipped by hand 
from true pitch lines. All brick-facing shall be bonded, as shown on plans, at 
least one-fifth of the face of the wall being headers. The brick must be of the 
best quality of hard-burned paving brick and must stand all tests as to dura- 
bility and fitness required by the engineer in charge. The bricks must be 
regular in shape and practically uniform in size and color. They shall be free 
from lime and other impurities ; shall be free from checks or fire cracks and 
as nearly uniform in every respect as possible ; shall be burned so as to secure 
the maximum hardness ; so annealed as to reach the ultimate degree of tough- 
ness, and be thoroughly vitrified so as to make a homogeneous mass. 

The backing shall be carried up simultaneously with the face work and 
be thoroughly bonded with it. 

The use of boulder facing will ordinarily be limited to structures of special 
character, and its success will depend very largely upon the care with which 
the stones are selected, their size and their arrangement in the structure. In 
constructing a boulder-faced concrete arch at Washington, D. C, the following 
requirements were specified for the facing : 

The term boulder here is meant to cover loose rock, which shall be hard, 
durable and of a quality to be approved by the engineer, whose edges have 
become weathered or water-worn, or both, and are more or less rounded. It 
is the intention to obtain a decidedly rustic effect on the facing, and to that 
end extreme care must be taken in the selection of the stones, and only 
mechanics who show an aptitude for this class of work shall be employed. No 
tool marks or fresh fractures will be allowed on the showing faces. 

The boulder face of such stone shall project at least 2 inches beyond the 
neat lines of the bridge, and this projection shall not exceed 15 inches, nor 
shall it be greater than one-half the least horizontal dimension of the stone. 
All joints shall be scraped and brushed clear of mortar to the depth indicated 
by the engineer. The mortar shall consist of 1 part Portland cement and 
2 parts sand. The backs of all boulders shall be plastered with a layer of 
mortar, as specified, at least % inch thick, immediately before ramming the 
concrete against them. 

The arch-stones shall have a depth of between 3 and -4 feet, a width of 
not less than 18 inches nor more than 36 inches, all dimensions to be measured 
exclusive of the projections beyond the neat lines. The joints shall be dressed 
so as not to exceed 1^ inches at any point for at least two-thirds their depth 
and two-thirds their length, and as much more as the stones will admit. Each 
arch-stone shall be cramped to the adjacent steel girder by means of a wrought- 
iron cramp made from ^ X S/^-inch bar, the cramps to reach at least 2 inches 
into each boulder, to be well cemented into them and securely cramped to the 
top of the girder. The outside girders shall be cramped to the adjacent girders 
by 10 wrought-iron cramps made from ^ x -Ms-inch bar (in construction we 
used 24 -inch, as it bent cold without fracture). 



54 American Steel and Wire Company 

No dressing will be required on the stones used in abutments, spandrels 
and wing walls of the work, but only well-shaped boulders, laid on their broadest 
bed, will be allowed. Dressing will be permitted on such stones as cannot be 
properly bedded without it. The parapet walls will be a continuation of the 
spandrel and wing walls. The boulder stone must reach entirely through 
the wall. 

Cast Concrete Slab Veneer In constructing the arch bridge at Soissons, 

France, which is described on page 244, the 
faces of the arch-ribs and the spandrel facing were formed of slabs of concrete 
steel molded separately and set in place like stone veneer, with the remainder 
of the concrete forming i backing. An essentially similar construction was 
employed in Chicago, 111., in 1902, in constructing a number of recreation 
buildings in one of the city parks. In the last example mentioned the slabs 
were cast face down in wooden molds, the mode of procedure being as follows : 

A layer of mortar, composed of 1 part cement and 2 or 3 parts of finely 
crushed stone, was first placed in the bottom of the mold to a depth of from 
y 2 inch to 1 inch ; on this bed of mortar a 1-2-4, concrete, with ^ to 24 -inch 
stone, was placed to the thickness desired and carefully rammed. After 
hardening, the blocks were removed from the molds and set aside to season 
until they were placed in the structure. 

The construction of the slab veneer for the Soissons Bridge was as follows : 
For molding the arch-rib facing a smooth level platform or pavement of con- 
crete was constructed on an adjacent level piece of ground. This molding 
platform was large enough to permit the arch-ribs to be delineated to full size 
on its surface. To prepare the mold the platform was covered smoothly with 
gunny cloth held down by battens, which also served to outline the extrados 
and intrados of the arch-rib. Radical strips of wood were then placed to divide 
the mold into voussoir-like sections. A thin bed of mortar was placed on the 
bottom of the mold and on this was laid four reinforcing-bars, one near and 
parallel to each edge of the voussoir being molded, so as to intersect at the 
corners. Under these bars at several points wire stirrups were looped with 
their fine ends projecting upward. The metal was then covered with a rich 
concrete of fine stone laid on the mortar bed and compacted so that the total 
thickness was about 2 inches. When hardened the product of the mold was 
a set of voussoir-shaped slabs with smooth faces and edges and a rough back 
with a number of projecting wires. In construction these facing slabs were 
set in place with mortar joints and backed with concrete. For the spandrel- 
wall facing the slabs were cast in rectangular molds in exactly the same manner. 
The engineers of the Soissons Bridge remark that the use of this cast concrete 
veneer enabled a considerable reduction of expense for forms and assured a 
surface finish of pleasing appearance. 

Moldings and Ornamental Shapes The finishing of concrete structures in 

many instances comprehends the con- 
struction of moldings and ornamental shapes for cornices, corbels, medallions, 
key-stones and other architectural parts. These may either be molded in place 



Concrete Reinforcement 55 



by suitable construction of the stationary forms or they may be cast separately' 
in portable molds and set in place in the structure as would be cut stone. Panels 
of simple form or plain cornice moldings can usually be molded in place without 
great trouble and expense, but in constructing corbels, complicated moldings, 
balusters, etc., particularly where one pattern is duplicated a number of times, 
time and expense will usually be saved by casting them separately or in sec- 
tions, and afterwards erecting the separate pieces in the structure. 

The casting of. ornamental shapes in concrete may be accomplished either 
in sand-molds or in rigid molds of wood, metal or plaster of Paris. Some very 
handsome work has been recently performed by sand-molding. The mode of 
procedure followed in making concrete castings in sand varies somewhat in 
practice, but it is substantially as follows : A pattern of the shape to be cast is 
first made in wood and to the exact size required, since no allowance for 
shrinkage is necessary. The pattern is then molded in sand in flasks exactly 
as is done in casting iron. The mixture used usually consists of cement and 
finely crushed stone of about the consistency of cream, and this is poured into 
the mold by means of a funnel and T-pipe. The excess water in the mixture 
soaks into the sand and serves to keep the casting moist during setting. 
Generally the casting is left in the mold for three or four days and is then 
removed, and the projecting fins, if any, are cut off. The cast stone may be 
used immediately in the work, but it is preferable to let it season and harden 
for a fortnight or more before using. The product of these sand-molds has an 
unusually attractive surface texture. Sand-molding is particularly advantageous 
when balusters, corbels, medallions and intricate moldings have to be cast, but 
for plain cornices and facing slabs it is generally as cheap and convenient to 
use wooden forms. 

Efflorescence The leaching out of certain lime compounds and their deposi- 
tion on the surfaces of concrete work are quite frequently the 
cause of the uneven color of such surfaces. In relation to this source of 
discoloration Mr. Clifford Richardson, director of the New York Testing 
Laboratory, says : 

'It is primarily due to variations in the amount of water in the mortar of 
which the cement is composed. It will be readily understood that, when any 
excess of water is used, segregation of the coarse and fine particles will take 
place, with a resulting difference in color. When a large amount of water is 
used the concrete is more porous and the very considerable percentage of free 
lime liberated from the Portland cement in the course of setting is more readily 
brought to the surface at such point. . . . The amount of water in a con- 
crete, the face of which is to be exposed, should be neither too small nor too 
large, but such a concrete should certainly not be dry or the exposed face will 
be honeycombed. . . . Where the greatest care is used as to the amount of 
water added to the mortar and to prevent its loss, and where separation of the 
mortar from the broken stone is carefully avoided in depositing the concrete 
and in ramming it, the exposed surface, after the removal of the molds, is fairly 
uniform in color. ... A more uniform color will always be obtained when 
some puzzolanic material is ground in with the cement, such as slag or tross. 



56 American Steel and Wire Company 



This hydrated silicious material combines with the lime which has been liber- 
ated and prevents it washing out on the surface. . . . Exactness in the 
amount of water used in the concrete, when the elimination of the stain caused 
by the free lime is considered desirable, and the addition of some substance con- 
taining silica in an active form, are the two steps to be taken to produce a 
concrete surface which should present a uniform color and a pleasing 
appearance. 



The measures whose adoption are recommended in the quotation just made 
are designed to prevent the occurrence of efflorescence by adopting certain pre- 
cautions in the materials and workmanship of the original construction. Their 
adoption, however, if it gives the success that Mr. Richardson anticipates, is 
obviously the way to get at the root of the trouble, but such action involves a 
degree of skill and watchfulness in constructing concrete work which is difficult 
of attainment under ordinary conditions of engineering construction, and which, 
if attained, will add materially to the cost of construction. They have the 
further objection that a special mixture of cement is required about which our 
information is not entirely certain. In default of preventive measures, which 
recommend themselves to general use, the engineer who encounters the trouble 
of efflorescence must overcome it by remedial measures. There are a number 
of these available. The most practical ones are the washing of the discolored 
surfaces by solution, which will remove the incrustation, or the removal of the 
original surface by dressing it down with hammers or tooling of some sort. 

The manner of dressing down concrete surfaces to eliminate surface 
imperfections is discussed in a previous paragraph. The following account of 
the method of cleaning a concrete-steel bridge at Washington, D. C, gives 
instructive data as to this mode of procedure : The bridge in question had a 
mortar facing, and after this was completed a heavy rain caused the entire 
north facade to become discolored by efflorescence. This discoloration was 
not uniform, but in streaks and blotches of a white color, which, after weather- 
ing a short time, turned into a dirty yellow. To clean the bridge, trial was first 
made of water and wire brushes, but after a little work this method was con- 
sidered impracticable owing chiefly to its cost, which was estimated at $2.40 
per square yard. Washes of dilute hydrochloric acid, of dilute acetic acid and 
of dilute oxalic acid were then tried in conjunction with ordinary scrubbing 
brushes. The hydrochloric-acid wash proved the best, and the acetic-acid wash 
came next in efficiency. The wash finally adopted consisted of a solution of 
X part hydrochloric acid and 5 parts water. This was applied vigorously with 



Concrete Reinforcement 57 



scrubbing brushes, water being constantly played on the work with a hose to 
prevent the penetration of the acid. One house-cleaner and five laborers were 
employed on the work, which cost GO cents per square yard. This high cost 
was due largely to the difficulty of cleaning the balustrades ; it was estimated 
that the cost of cleaning the spandrel and wing walls did not exceed 20 cents 
per square yard. The cleaning was thoroughly satisfactory. Some of the 
flour removed by the brushes was analyzed and found to be silicate of lime. 



58 



American Steel and Wire Company 



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Concrete Reinforcement 



59 



Volume of Plastic Mortar made from Different Proportions of 

Cement and Sand 

Quantities of Materials Per Cubic Yard 

(See page 237) 
(Reprinted by permission from Taylor & Thompson's " Concrete, Plain and Reinforced," page 229) 



Relative 

Proportions 

by 

Volume* 


Volume of Compacted Plastic Mortar 


Materials for 1 Cubic Yard Cnmnart Plastir 


From 1 Cu. Ft. 


Cement 


From 1 Barrel Cement 




Mortar Based on Barrel of 




Based on Portland 


Based on Barrel 
















Cement Weighing 




of 


3.5 Cubic Feet 


3.8 Cub 


icFeett 


4 Cubic Feet 






o 


-i— 


o 




h— 






nd 


a 

u 


•o 




id 


c 

4) 

a 


T3 
C 
ni 


£1 


1* 

3 o 


T3fa 

fa 3 


fa 

o 

-2 


fa 
IS 


<u 

fa 

o 

"rO 


E 
O 


a 
a 
in 

<u 


a 

U 


e 

V 


E 

CD 
U 


c 

ni 

W 


O 




qo O 
o 
•t-l >~ 


§u 






u 


U 




O 


u 
u 


o 
o 

_1 




o 
o 






p. 


u 

a 


a 


eo 


r*3 




fa 




a- . 




fa 








cu. ft. 


cu. ft. 


cu. ft. 


cu. ft. 


CU. ft. 


cu. ft. 


bbl. 


cu. yd. 


bbl. 


cu.yd. 


bbl. 


cu. yd. 







0,93 


0.86 


0.80 


3.2 


3.2 


3.2 


8.31 




8.31 




8.31 






% 


1.12 


1.06 


1.02 


3.9 


4.0 


4.1 


6.92 


0.46 


6.73 


0.47 


6.61 


0.49 




1 


1.48 


1.42 


1.38 


5.2 


5.4 


5.5 


5.22 


0.68 


5.01 


0.71 


4.88 


0.72 




IK 


1.84 


1.78 


1.74 


6.4 


6.7 


7.0 


4.20 


0.81 


4.00 


0.84 


3.87 


0.86 




2 


2.20 


2.14 


2.11 


7.7 


8.1 


8.4 


3.51 


0.91 


3.32 


0.93 


3.21 


0.95 




2% 


2.56 


2.50 


2.47 


9.0 


9.5 


9.9 


3.01 


0.98 


2.84 


1.00 


2.74 


1.01 




3 


2.92 


2.86 


2.83 


10.2 


10.9 


11.3 


2.64 


1.03 


2.48 


1.05 


2.39 


1.06 




sv 2 


3.28 


3.23 


3.19 


11.5 


12.2 


12.8 


2.35 


1.06 


2.20 


1.08 


2.12 


1.10 




4 


3.64 


3.59 


3.55 


12.8 


13.6 


14.2 


2.12 


1.10 


1.98 


1.11 


1.90 


1.13 




4% 


4.01 


3.95 


3.91 


14.0 


15.0 


15.6 


1.92 


1.12 


1.80 


1.14 


1.72 


1.15 




5 


4.37 


4.31 


4.28 


15.3 


16.4 


17.1 


1.7? 


1.15 


1.65 


1 16 


1.58 


1.17 




5y 2 


4.73 


4.67 


4.64 


16.6 


17.7 


18.5 


1.63 


1.16 


1.52 


1.18 


1.46 


1.19 




6 


5.09 


5.03 


5 00 


17.8 


19.1 


20.0 


1.52 


1.18 


1.41 


1.19 


1.35 


1.20 




ay?, 


5.45 


5.39 


5.36 


19.1 


20.5 


21.4 


1.41 


1.19 


1.32 


1.21 


1.26 


1.21 




7 


5.81 


5.76 


5.72 


20.3 


21.9 


22.9 


1.33 


1.21 


1.23 


1.21 


1.18 


1.22 




7% 


6.18 


6.12 


6.08 


21.6 


23.2 


24.3 


1.25 


1.21 


1.16 


1.22 


1.11 


1.23 


1 


8 


6 54 


6.48 


6.44 


22.9 


24 6 


25.8 


1.18 


1.22 


1.10 


1 24 


1.05 


1.24 



Note— Variations in the fineness of the sand and the cement, and in consistency of the mortar may affect the 
values by 10 per cent in either direction. 

*Cement as packed by manufacturer, sand loose. 
t Use these columns ordinarily. 



60 



American Steel and Wire Company 



Quantities of Materials for One Cubic Yard of Rammed Concrete 
Based on a Barrel of 3.5 Cubic Feet 

(See important foot-notes, also page 225) 
(Reprinted by permission from Taylor & Thompson's " Concrete, Plain and Reinforced," page 230) 



Proporti 


ons 
s 


Proportions 


Volume 
of Mortar 
in Terms 

of Per- 


Percentages of Voids in Broken Stone or Gravel 


by Pan 


by Volumes 


50£* 


45#t 


40St 


30^§ 


2%% 










«frt 
1/1 r* 






•d 


4) 

a 




a 


c 




c 


V 

a 


a 

<u 


a 


c 




nd 


a 


a 

V 


-a 


a 


tie 

re i> 


5 


•JCO 


centage of 


s 


re 

CO 





6 

1> 


re 

CO 


CO 


4) 


CO 


CO 


a 

CI 


re 
in 


C/2 


E 


re 
C/2 




CO 


F 


re 




IhU 


Volume 


U 






U 






U 






U 






CJ 






41 

(J 


co 


CO 








of Stone 



































1 


bbl. 


cu. 
ft. 


cu. 

ft. 




bbl. 


cu 

yd. 


cu. 

yd. 


bbl. 
5.07 


cu 
yd 


cu 

yd. 

0.66 


bbl. 
4.89 


cu. 

yd. 


cu. 
yd. 

0.63 


bbl. 
4.51 


cu. 

yd. 


CU. 

yd. 
0.58 


bbl. 
4.19 


CU 

yd 


CU. 

yd. 




3 5 


101 


5.25 




0.68 


0.54 








2 






7.0 


54 


3.84 




1.00 


3.64 




0.94 


3.47 




0.90 


3.09 




0.80 


2.80 




0.7'3 








8 






10.5 


39 








2.85 




1.11 


2.69 


. . . 


1.05 


2.35 




0.91 


2.10 




0.82 








4 






14.0 


31 






































5 






17.5 


27 
























1 03 


1.41 




91 








6 






21.0 


24 
























1 07 


1.21 




0.94 








7 






24.5 


21 






































8 
9 






28.0 
31.5 


20 
18 


























94 




9R 




































10 






35.0 


17 






































11 






38.5 


16 






































12 






42.0 


16 


































1 


■m 




3.5 


5.2 


104 


3.37 


0.44 


0.65 


S 26 


0.42 


0.63 


3.15 


0.41 


0.61 


2.95 


0.38 


0.57 


2.78 


0.36 


0.54 




1 


2 




8.5 


7.0 


78 


3.02 


0.39 


0.78 


2.89 


0.38 


0.75 


2.78 


0.36 


0.72 


2.58 


0.33 


0.67 


2.41 


0.31 


0.62 




1 


2% 




3.5 


8.7 


64 


2.73 


0.35 


0.88 


2.60 


0.34 


0.84 


2.49 


0.32 


0.80 


2.29 


0.30 


0.74 


2.12 


0.28 


0.68 




1 


3 




3 5 


10.5 


54 


2 49 


0.32 


0.97 


2.37 


0.81 


0.92 


2.25 


0.29 


0.88 


2.06 


0.27 


0.80 


1.90 


0.25 


0.74 




1« 


2 




5 2 


7.0 


95 


2.64 


0.51 


0.68 


2.55 


0.49 


0.66 


2.46 


0.47 


0.64 


2.30 


0.44 


O.60 


2.16 


0.42 


0.56 




IK 


2V,, 




5.2 


8.7 


78 


2.42 


0.47 


0.78 


2.32 


0.45 


0.75 


2.23 


0.43 


0.72 


2.07 


0.40 


0.67 


1.93 


0.37 


0.62 




1 l A 


8 




5.2 


10.5 


65 


2 23 


0.43 


0.87 


2.13 


0.41 


0.83 


2.04 


0.39 


0.79 


1.88 


0.36 


0.73 


1.74 


0.34 


0.68 




V* 


3^ 




5.2 


12.2 


56 


2.07 


0.40 


0.94 


1.97 


0.38 


0.89 


1.88 


0.36 


0.85 


1.72 


0.33 


0.78 


1.59 


0.31 


0.72 




VA 


4 




5.2 


14.0 


50 


1.93 


0.37 


1.00 


1.83 


0.35 


0.95 


1.74 


0.34 


0.90 


1.59 


0.31 


0.82 


1.46 


0.28 


0.76 




1Vf 


4Vf 




5.2 


15.7 


45 


1.81 


0.35 


1.05 


1.71 


0.33 


0.99 


1.62 


0.31 


0.94 


1.47 


0.28 


0.86 


1.35 


0.26 


0.78 




n* 


5 




5 2 


17.5 


41 


1.70 


0.33 


1.10 


1.60 


0.31 


1.04 


1.52 


0.29 


0.99 


1.37 


0.26 


0.89 


1.25 


0.24 


0.81 




2 


3 




7.0 


10.5 


77 


2.02 


0.52 


0.79 


1.94 


0.50 


0.75 


1.86 


0.48 


0.72 


1.73 


0.45 


0.67 


1.61 


0.42 


0.63 




2 


8^ 




7 


12.2 


67 


1.89 


0.49 


0.85 


1.80 


0.47 


0.81 


1.73 


0.45 


0.78 


1.59 


0.41 


0.72 


1.48 


38 


0.67 




2 


4 




7.0 


14 


59 


1.77 


0.46 


0.92 


1.69 


0.44 


0.88 


1.61 


0.42 


0.83 


1.48 


0.88 


0.77 


1.37 


0.35 


0.71 




2 


4fc 




7.0 


15.7 


53 


1.67 


43 


0.97 


1.58 


0.41 


0.92 


1.51 


0.39 


0.88 


1.38 


0.36 


0.80 


1.27 


0.33 


0.74 




2 


5 




7.0 


17.5 


48 


1.57 


0.41 


1.02 


1.49 


0.39 


0.97 


1.42 


0.37 


0.92 


1.29 


0.33 


0.84 


1.18 


0.81 


0.76 




2 


5^ 




7.0 


19.2 


44 


1.49 


0.39 


1.06 


1.41 


0.36 


1.00 


1.34 


35 


0.95 


1.21 


0.31 


0.86 


1.11 


0.29 


0.79 




2 


6 




7.0 


21.0 


41 


1.42 


0.37 


1.10 


1.34 


0.35 


1.04 


1.27 


0.33 


0.99 


1.14 


0.30 


0.89 


1.04 


0.27 


0.81 




2% 


3 




8.7 


10 5 


90 


1.84 


0.59 


0.72 


1.78 


0.57 


0.69 


1.71 


0.55 


0.66 


1.6C 


0.52 


0.62 


1.50 


0.48 


0.58 




2Vf 


3Vf 




8.7 


12.2 


78 


1.73 


0.56 


0.78 


1.66 


0.53 


0.75 


1.60 


0.52 


0.72 


1.48 


0.48 


0.67 


1.38 


0.44 


62 




2y 2 


4 




8.7 


14.0 


68 


1.63 


0.52 


0.85 


1.56 


0.50 


0.81 


1.50 


0.48 


0.78 


1.38 


0.44 


0.72 


1.28 


0.41 


0.66 




2% 


4VC 




8.7 


15.7 


61 


1.55 


0.50 


0.90 


1.47 


0.47 


0.86 


1.41 


0.45 


0.82 


1.29 


0.42 


0.75 


1.20 


0.39 


0.70 




2% 


5 




8.7 


17.5 


55 


1.47 


0.47 


0.95 


1.39 


0.45 


0.9U 


1.33 


0.43 


0.86 


1.22 


0.39 


0.79 


1.12 


0.36 


0.73 




2% 


5^ 




8.7 


19.2 


51 


1.39 


0.45 


0.99 


1.32 


0.42 


0.94 


1.26 


0.41 


0.90 


1.15 


0.37 


0.82 


1.06 


0.34 


0.75 




2% 


6 




8.7 


21.0 


47 


1.33 


0.43 


1.03 


1.26 


0.41 


0.98 


1.20 


0.39 


0.93 


1.09 


0.35 


0.85 


1.00 


0.32 


0.78 




2V ? 


Btf 




8.7 


22.7 


44 


1.27 


0.41 


1.07 


1.20 


0.39 


1.01 


1.14 


0.37 


0.96 


1.03 


0.33 


0.87 


0.94 


0.30 


0.79 




2% 


7 




8.7 


24.5 


41 


1.22 


0.39 


1.11 


1.15 


0.37 


1.04 


1.09 


0.35 


0.99 


0.98 


0.32 


0.89 


0.90 


0.29 


0.82 




3 


4 




10.5 


14.0 


77 


1.52 


0.59 


0.79 


1.46 


0.57 


0.76 


1.40 


0.54 


0.73 


1.30 


0.50 


0.67 


1.21 


0.47 


0.63 




3 


4VC 




10.5 


15.7 


69 


1.44 


56 


0.84 


1.38 


0.54 


0.80 


1.32 


0.51 


0.77 


1.22 


0.47 


0.71 


1.13 


0.44 


0.66 




3 


5 




10.5 


17.5 


62 


1.37 


0.53 


0.89 


1.31 


0.51 


0.85 


1.25 


0.48 


0.81 


1.15 


0.45 


0.75 


1.07 


0.42 


0.69 




3 


5K 




10.5 


19 2 


57 


1.31 


51 


0.93 


1.25 


0.48 


0.89 


1.19 


0.46 


0.85 


1.09 


0.42 


0.78 


1.01 


0.39 


0.72 




8 


6 




0.5 


21.0 


53 


1.25 


0.48 


0.97 


1.19 


0.46 


0.93 


1.13 


0.44 


0.88 


1.03 


0.40 


0.80 


0.95 


0.37 


0.74 




3 


6fc 




10.5 


22.7 


49 


1.20 


0.47 


1.01 


1.14 


C.44 


0.96 


1.08 


0.42 


0.91 


0.98 


0.38 


0.82 


0.90 


0.35 


0.76 




3 


7 




10.5 


24.5 


46 


1.15 


0.45 


1.04 


1.09 


0.42 


0.99 


1.03 


0.40 


0.93 


0.94 


0.36 


0.85 


0.86 


0.33 


0.78 




3 


IV, 




10.5 


26.2 


43 


1. 11 


0.43 


1.08 


1.05 


0.41 


1.02 


0.99 


0.38 


0.96 


0.90 


0.35 


0.87 


0.82 


0.32 


0.80 




3 


8 




10.5 


28.0 


40 


1.06 


0.41 


1.10 


1.01 


0.39 


1.05 


0.95 


0.37 


0.99 


0.86 


0.33 


0.89 


0.78 


0.30 


0.81 




4 


5 




14.0 


17.5 


77 


1.22 


0.63 


0.79 


1.17 


0.61 


76 


1.12 


0.58 


0.73 


1.04 


0.54 


0.67 


0.97 


0.50 


63 




4 


6 




14.0 


21 


65 


1 12 


0.58 


0.87 


1.07 


0.55 


0.83 


1.02 


0.53 


0.79 


0.94 


0.49 


0.73 


0.87 


0.45 


0.68 




4 


7 




14.0 


24 5 


56 


1.04 


0.54 


0.94 


0.99 


0.51 


0.90 


0.94 


0.49 


0.85 


0.86 


0.41 


0.78 


0.80 


0.41 


0.73 




4 


8 




14.0 


28 


50 


0.97 


0.50 


1.01 


0.92 


0.48 


0.95 


0.87 


0.45 


0.90 


0.80 


0.41 


0.83 


0.73 


0.38 


0.76 




4 


9 




14.0 


31 5 


45 


0.91 


0.47 


1.06 


0.86 


0.44 


1.00 


0.81 


0.42 


0.94 


0.74 


0.38 


0.86 


0.68 


0.85 


0.79 




4 


10 




14.0 


35.0 


41 


0.85 


0.44 


1.10 


0.81 


0.42 


1.05 


0.76 


0.39 


0.98 


0.69 


0.36 


0.89 


0.63 


0.33 


0.82 




5 


10 




17 5 


35 


48 


79 


51 


1.02 


0.75 


0.49 


97 


0.71 


0.46 


0.92 


0.65 


0.42 


0.84 


0.59 


0.38 


0.76 




6 


12 




21.0 


42.0 


46 


10.67 


0.52 


1.04 


0.63 


0.49 


0.98 


0.60 


0.47 


0.93 


0.54 


0.42 


0.84 


50 


0.39 


0.78 



Note — Variations in the fineness of the sand and the compacting of the concrete may affect the quantities by 
10 per cent in either direction. 

*Use 50 per cent columns for broken stone screened to uniform size. tUse 45 per cent columns for average 
conditions and for broken stone with dust screened out. JUse 40 per cent columns for gravel or mixed stone and 
gravel. §Use these columns for scientifically graded mixtures. 



Concrete Reinforcement 



61 



Quantities of Materials for One Cubic Yard of Rammed Concrete 
Based on a Barrel of 3.8 Cubic Feet 

(See important foot-notes, also page 225) 
(Reprinted by permission from Taylor & Thompson's " Concrete, Plain and Reinforced," page 231) 



Proportions 


Proportions 


Volume 
of Mortar 


Percentages cf Voids in Broken Stone or Gravel 


by Parts 


by Volumes 


50^* 


45^t 


40« 


W4 


2W§ 








., 






j 






+, 






^ 






+J 






^ 






c 

<U 

s 

<U 


e 

d 

co 


CU 

c 
o 

•co 
1 


O c 

OhCJ 


™ 


§! 


of Per- 
centage of 

Volume 
" of Stone 


c 
6 
U 


-a 
a 

CO 


c 


to 


S3 

CU 

s 

<u 




a 

d 
CO 


c 


Co 


a 

<u 

S 

CU 




T3 

C 

a 

CO 


c 


CO 


S 

CU 




a 

CO 


c 


CO 


c 

CU 

£ 

CU 




•0 

c- 
ra 
CO 


CU 

C 
O 

CO 


u 




bbl. 


CU. 
ft. 


CU. 

ft. 


bbl. 
5.09 


CU. 

yd 


CU 

yd. 
0.72 


bbl. 
4.90 


CU. 

yd. 


CU. 

yd. 


bbl. 


CU. 

yd. 


CU. 

yd. 


bbl. 


CU. 

yd 


CU. 

yd. 
0.61 


bbl. 

4.02 


CU. 

yd. 


CU. 

yd. 








3 8 


94 




0.69 


4.73 




0.67 


4.33 


0.57 






a 






7 6 


51 


3.67 




1.03 


3.48 




0.98 


3.30 


■ . . 


0.93 


2.93 




82 


2.65 


... . 


0.75 






3 






11.4 


36 








2.69 




1.14 


2.54 




1.07 


2.22 




0.94 


1.98 




0.84 






4 






15 2 


29 
























1 00 


1.58 




0.89 






5 
6 






19.0 

22.8 


25 

22 




















1 4°) 




1.05 


1.31 
1.12 




92 
























0.95 






7 






26.6 


20 




































8 






30.4 


19 


























0.87 


. . • 


0.98 






9 






34.2 


18 




































10 






38.0 


17 


























0.71 










11 






41.8 


16 




































12 






45.5 


15 






























1.01 




1 


1% 




3.8 


5,7 


99 


3.19 


0.45 


0.67 


3.08 


0.43 


0.65 


2.97 


0.42 


0.63 


2.78 


0.39 


0.59 


2.62 


0.37 


55 




1 


2 




3.8 


7 6 


75 


2.85 


0.40 


0.80 


2.73 


0.38 


0.77 


2.62 


0.37 


0.74 


2.43 


034 


0.68 


2.26 


0.32 


0.64 




1 


2 l /£ 




3.8 


9.5 


61 


2.57 


0.36 


0.90 


2.45 


o.34 


0.86 


2.34 


0.33 


0.82 


2.15 


0.30 


0.76 


1.99 


0.28 


0.70 




1 


3 




3.8 


11 4 


51 


2.34 


0.33 


0.99 


2.22 


0.31 


0.94 


2.12 


0.30 


0.90 


1.93 


0.27 


0.82 


1.77 


0.25 


0.75 




1^ 


2 




5.7 


7 6 


93 


2.49 


0.53 


0.70 


2.40 


0.51 


0.68 


2.31 


0.49 


0.65 


2.16 


0.46 


0.61 


2.03 


<?.43 


0,57 




1% 


2% 




5.7 


9.5 


76 


2.27 


0.48 


0.80 


2.18 


0.46 


0.77 


2.09 


0.44 


0.74 


1.94 


0.41 


0.68 


1.80 


0.38 


0.63 




Wr, 


3 




5.7 


11.4 


64 


2.09 


0.44 


0.88 


2.00 


0.42 


0.84 


1.91 


0.40 


0.81 


1.76 


0.37 


0.74 


1.63 


0.34 


0.69 




VA 


WA 




5.7 


13 3 


55 


1.94 


0.41 


0.96 


1.84 


0.39 


0.91 


1.76 


0.37 


0.87 


1.61 


0.34 


0.79 


1.48 


0.31 


0.73 




VA 


4 




5.7 


15.2 


49 


1.80 


0.38 


1.01 


1.71 


0.36 


0.96 


1.63 


0.34 


0.92 


1.48 


0.31 


0,83 


1.36 


0.29 


0.77 




IV* 


41/ 




5.7 


17.1 


44 


1.69 


0.36 


1.07 


1.60 


0.34 


1.01 


1,51 


0.32 


0.96 


1.37 


029 


0.87 


1.25 


0.26 


0.79 




\v« 


5 




5.7 


19.0 


40 


1.59 


0.34 


1 12 


1.50 


0.32 


1.06 


1.42 


0.30 


1.00 


1.28 


0.27 


0.90 


1.17 


0.25 


0.82 




2 


3 




7.6 


11.4 


75 


1.89 


0.53 


0.80 


1.81 


0.51 


0.76 


1.74 


0.49 


0.74 


1.61 


0.45 


0.68 


1.50 


0.42 


0.63 




2 


8VC 




7.6 


13. 3 


65 


1.76 


0.49 


0.87 


1.68 


0.47 


0.83 


1.61 


0.45 


079 


1.48 


0.42 


0.73 


1.38 


0.39 


0.68 




2 


4 




7.6 


15.2 


57 


1.65 


0.46 


0.93 


1.57 


44 


0.88 


1.50 


0.42 


0.84 


1.38 


0.39 


0.78 


1.27 


0.36 


0.72 




2 


4% 




7.6 


17.1 


51 


1.55 


0.44 


0.98 


1.48 


0.42 


0.94 


1.41 


0.40 


0.89 


1.28 


0.36 


0.81 


1.18 


0.33 


0.75 




2 


5 




7.6 


19.0 


47 


1.47 


41 


1.03 


1.39 


0.39 


0.98 


1.32 


37 


0.93 


1.20 


0.34 


0.84 


1.10 


0.31 


0.77 




2 


5U 




7.6 


20.9 


43 


1 39 


0.39 


1.08 


1.31 


0.37 


1.01 


1.25 


0.35 


0.97 


1.13 


0.32 


0.87 


1.03 


0.29 


0.80 




2 


6 




7.6 


22.8 


40 


1.32 


0.37 


1.11 


1.25 


0.35 


1.06 


1.18 


0.33 


1.00 


1.06 


0.30 


0.89 


0.97 


0.27 


0.82 




2% 


3 




9.5 


11.4 


87 


1.72 


0.61 


0.73 


1.66 


0.58 


0.70 


1.60 


0.56 


0.68 


1.49 


0.52 


0.63 


1.40 


0.49 


0.59 




2V ? 


8V5 




9.5 


13.3 


75 


1.62 


0.57 


0.80 


1.55 


0.55 


0.76 


1.49 


0.52 


0.73 


1.38 


0.49 


0.68 


1.29 


0.45 


0.64 




2% 


4 




9.5 


15.2 


66 


1.52 


0.54 


0.86 


1.46 


0.51 


0.82 


1.40 


0.49 


0.79 


1.29 


0.45 


0.73 


1.19 


0.42 


0.67 




2Vo 


4* 




9.5 


17.1 


60 


1.44 


0.51 


0.91 


1.37 


0.48 


0.87 


1.31 


0.46 


0.83 


1.20 


0.42 


0.76 


1.11 


0.39 


0.70 




2V 9 


5 




9.5 


19.0 


54 


1.37 


0.48 


0.96 


1.30 


0.46 


0.92 


1.24 


0.44 


0.87 


1.13 


0.40 


0.80 


1.04 


0.37 


0.73 




2% 


5V 2 




9.5 


20.9 


49 


1.30 


46 


1.01 


1 23 


0.43 


0.95 


1.17 


0.41 


0.91 


1.07 


0.38 


0.83 


0.98 


0.34 


0.76 




2Vo 


6 




9.5 


22.8 


46 


1.24 


0.44 


1.05 


1.17 


0.41 


0.99 


1.11 


0.39 


0.94 


1.01 


0.36 


0.85 


0.92 


0.32 


0.78 




2V 7 


6* 




9.5 


24.7 


42 


1.18 


0.42 


1.08 


1.12 


0.39 


1.02 


1.06 


0.37 


0.97 


0.96 


0.34 


0.88 


0.88 


0.31 


0.80 




2% 


7 




9.5 


26.6 


40 


1.13 


0.40 


1.11 


1.07 


0.38 


1.05 


1.01 


0.36 


0.99 


0.91 


0.32 


0.90 


0.83 


0.29 


0.82 




3 


4 




11.4 


15.2 


76 


1.42 


0.60 


0.80 


1.36 


0.57 


0.77 


1.30 


0.55 


0.73 


1.21 


0.51 


0.68 


1.12 


0.47 


0.63 




3 


4* 




11.4 


17.1 


68 


1.34 


0.57 


0.85 


1.28 


0.54 


0.81 


1.23 


0.52 


0.78 


1.13 


0.48 


0.72 


1.05 


0.44 


0.66 




3 


5 




11.4 


19.0 


61 


1.28 


0.54 


0.90 


1.22 


0.52 


0.86 


1.17 


0.49 


0.82 


1.07 


0.45 


0.75 


0.99 


0.42 


0.70 




3 


SVC 




11.4 


20.9 


56 


1.22 


0.52 


0.94 


1.16 


0.49 


0.90 


1.11 


0.47 


0.86 


1.01 


0.43 


0.78 


0.93 


0.30 


0.72 




3 


6 




11.4 


22.8 


52 


1.16 


0.49 


0.98 


1.11 


0.47 


0.94 


1.05 


0.44 


0.89 


0.96 


0.41 


0.81 


0.88 


0.37 


0.74 




3 


VA 




11.4 


24.7 


48 


1.12 


0.47 


1.054 


1.06 


0.45 


0.97 


1.01 


0.43 


0.92 


0.92 


0.39 


0.84 


0.84 


0.35 


0.77 




3 


7 




11.4 


26.6 


45 


1.07 


0.45 


1.05 


1.01 


0.43 


0.99 


0.96 


0.40 


0.95 


0.87 


0.37 


0.86 


0.80 


0.34 


0.79 




3 


m 




11.4 


28.5 


42 


1.03 


0.44 


1.09 


0.97 


0.41 


1.02 


0.92 


0.39 


0.97 


0.83 


0.35 


0.88 


0.76 


0.32 


0.80 




3 


8 




11.4 


30.4 


40 


0.99 


0.42 


1.11 


0.93 


0.39 


1.05 


0.88 


0.37 


0.99 


0.80 


0.34 


0.9U 


0.73 


0.31 


0.82 




4 


5 




15.2 


19.0 


76 


1.13 


0.61 


0.80 


1.08 


0.61 


0.76 


1.04 


0.59 


073 


0.96 


0.54 


0.68 


0.90 


0.51 


0.63 




4 


6 




15.2 


22.8 


64 


1.04 


0.59 


0.88 


0.99 


0.56 


84 


0.95 


0.54 


0.80 


0.87 


0.49 


0.73 


0.81 


0.46 


0.68 




4 


7 




15.2 


26.6 


55 


0.96 


0.54 


0.95 


0.92 


0.52 


0.91 


0.88 


0.50 


0.87 


0.80 


0.45 


0.79 


0.74 


0.42 


0.73 




4 


8 




15.2 


30.4 


49 


0.90 


0.51 


1.01 


0.85 


0.48 


0.96 


0.81 


0.46 


0.91 


0.74 


0.42 


0.83 


0.68 


0.38 


0.77 




4 


9 




15.2 


34.2 


44 


0.84 


0.47 


1.06 


0.80 


0.45 


1.01 


0.76 


0.43 


0.96 


0.68 


0.38 


0.86 


0.63 


0.35 


0.80 




4 


10 




15.2 


38.0 


40 


0.79 


0.44 


1.11 


0.75 


0.42 


1.06 


0.71 


0.40 


1.00 


0.64 


0.36 


0.90 


0.58 


0.33 


0.82 




5 


10 




19.0 


38. r 


47 


0.73 


0.52 


1.03 


0.69 


0.49 


0.97 


0.66 


0.46 


0.93 


0.60 


0.42 


0.84 


0.55 


0.39 


0.77 




6 


12 




22.8 


45.5 


46 


0.62 


0.52 


1.04 


0.58 


0.49 


0.98 


0.56 


0.47 


0.94 


0.50 


0.42 


0.84 


0.46 


0.39 


0.78 



Note — Variations in the fineness of the sand and the compacting of the concrete may affect the quantities 
10 per cent in either direction. 

*Use 50 per cent columns for broken stone screened to uniform size. tUse 45 per cent columns for average 
conditions and for broken stone with dust screened out. +Use 40 per cent columns for gravel or mixed stone and 
vel. §Use these columns for scientifically graded mixtures. 



62 



American Steel and Wire Company 



Quantities of Materials for One Cubic Yard of Rammed Concrete 
Based on a Barrel of 4 Cubic Feet 

(See important foot-notes, also page 225) 
(Reprinted by permission from Taylor & Thompson's " Concrete, Plain and Reinforced," page 232) 



Proportions 
by Parts 



1 
1 

1 

1 

V6 

iy 2 
ik 

2 

2 

2 
2 

2 
2 
2 

2K 

2K 
2K 

2 l A 
2V 2 
2 l A 

2y 2 

2 l A 

zy 2 

3 
3 
3 
3 
3 
3 

3 
3 
3 

4 
4 
4 

4 
4 
4 

5 
6 



10 
11 
12 

VA 
2 

2K 

3 

2 

2K 

3 

3K 
4 

4K 

5 

3 

3% 
4 

4K 
5 

5K 
6 

3 

3K 
4 

4K 
5 

5K 

6 

6K 

7 

4 

4K 
5 

5K 
6 

6% 

7 

7K 
8 

5 

6 

7 

8 

9 
10 
10 
12 



Proportions 
ty Volumes 



•SE 



bbl. 



jw 



10 
10 
10 
10 
10 
10 

1(1 

10 

10 

12 16 






cu. 

ft. 



Volume 
of Mortar 
in Terms 

of Per- 
centage of 

Volume 

of Stone 



89 
49 
35 

28 
24 

22 

20 
18 
17 

16 
15 
15 

96 
73 
59 

50 
92 
74 
62 
54 
48 
43 
39 
74 

64 
56 
51 

46 
42 
39 
86 
75 
66 
59 
54 
49 
45 
42 
39 

75 

67 
60 

55 

50 
48 
44 
42 
39 

75 

63 
55 

48 
43 
40 

47 
46 



Percentages of Voids in Broken Stone or Gravel 



50$* 



bbl 



4.99 
3.57 



8 
2 

2 

2 

2 
2 

2 

1 

1 

1 

1 

1 

1, 

1 

1 

1, 

1, 

1. 

1.65 

1.55 

1.46 

1.38 
1.31 
1.24 

1.18 
1.13 
1.08 
1.35 
1.28 
1.22 

1.16 
1.11 

1.06 
1.02 
0.98 
0.94 

1.08 
0.99 
0.92 

0.86 
0.80 
0.75 



yd. 



0.46 
0.41 
0.37 
0.33 
0.53 
0.48 
0.45 
0.41 
0.38 

0.36 
0.34 
0.54 
0.50 
0.47 
0.44 
0.42 
0.39 
0.37 

0.61 
0.57 
0.54 
0.51 
0.48 
0.46 
0.44 
0.42 
0.40 
0.60 
0.57 
0.54 
0.52 
0.49 
0.47 
0.45 
0.44 
0.42 
0.64 
0.59 
0.54 
0.51 
0.47 
0.44 



70 0.52 
59 0.52 



cu. 

yd. 



0.74 
1.06 



0, 

0, 


1 

0. 

0. 


u. 
1, 
1, 
1. 

0. 
0. 
0. 
0. 

1. 
1. 

1.12 
0.73 
0.80 
0.87 
0.92 
0.97 
1.01 



1.05 
1.09 
1.12 
0.80 
0.85 
0.90 
0.95 
0.99 
1.02 
1.06 
1.09 
1.11 

0.80 
0.88 
0.95 

1.02 
1.07 
1.11 

1.04 
1.05 



45^t 



U 



bbl. 



4.80 
3.37 
2.60 



97 

m 

35 
13 
30 

09 

91 
77 
64 

53 
43 

74 

61 
51 
41 
33 

20 
19 
59 
48 
39 

31 
24 

18 
12 
07 
02 

30 

23 

16 
11 
06 
01 
97 
93 
89 
03 
95 
88 
81 
78 
71 

0.66 
56 



cu. 
yd. 



0.44 
0.39 
0.35 
0.32 
0.51 
0.46 
0.42 
0.39 
0.36 
0.34 
0.32 
0.52 

0.48 
0.45 
0.42 
0.39 
0.37 
0.35 

0.59 
0.55 
0.51 
0.48 
0.46 
0.44 
0.41 
0.40 
0.38 

0.58 
0.55 
0.52 
0.49 
0.47 
0.45 

0.43 
0.41 
0.40 
0.61 
0.56 
0.52 

0.48 
0.45 
0.42 

0.49 
0.50 



0.71 
1.00 
1.16 



0.66 
0.78 
0.87 

0.95 
0.68 
0.77 
0.85 
0.92 
0.97 
1.02 
1.06 
0.77 
0.83 
0.89 
0.94 
0.98 
1.03 
1.06 

0.71 
0.77 
0.82 

0.87 
0.92 
0.96 

1.00 
1.03 
1.06 

0.77 
0.82 
0.86 





0, 

1. 
1. 
1. 

0. 
0. 
0. 

0.96 
1.01 
1.05 

0.98 
1.00 



40» 



U 



bbl. 



4.62 
3.20 
2.45 



2.87 

2.52 

2.25 

2.03 

2.22 

2.01 

1. 

1.68 

1.56 



cu. 
yd. 



0.42 
0.37 
0.33 
0.30 
0.49 
0.45 
0.41 
0.37 
0.35 
0.32 
0.30 
0.50 

0.46 
0.43 
0.40 

0.37 
0.35 
0.34 

0.57 
0.52 
0.49 

0.46 
0.44 
0.41 
0.39 
0.37 
0.36 

0.56 
0.52 
0.49 



1.53 
1.42 
1.33 

1.25 
1.18 
1.12 

1.06 
1.01 
0.96 
1.25 
1.18 
1.11 

1.06 
1.01 
0.96 
0.92 
0.88 
0.84 
0.99 
0.91 
0.83 

0.77 
0.72 
0.67 

0.63 0.47 
53 0.47 





0. 
0. 
0. 
0. 
0. 
0. 
0. 

0.46 
0.43 
0.40 



0.69 
0.95 
1.09 



0.64 
0.75 
0.83 
0.90 
0.66 
0.74 
0.81 
0.87 
0.92 
0.97 
1.00 
0.74 
0.80 
0.85 
0.89 

0.93 
0.97 
1.00 

0.68 
0.74 
0.79 
0.83 
0.87 
0.91 

0.94 
0.97 
1.00 

0.74 
0.79 
0.82 

0.86 
0.90 
0.92 
0.95 
0.98 
1.00 
0.73 
0.81 
0.86 
0.91 
0.96 
0.99 
0.93 
0.94 



20£§ 



U 



bbl 



4.23 
2.84 
2.13 
1.71 



1.43 
1.22 



2.69 
2.33 
2.06 
1.85 

2.0' 
1.86 

1.68 
1.54 
1.42 



1 
1 
1 
1 
1 
1 

1 

1 

1.02 

1.42 

1.32 

1.23 

1.15 

1. 

1.02 

0.96 
0.92 
0.87 
1.15 
1.08 
1.02 





0. 
0. 
0, 
0, 

0, 
0, 
0. 

0.70 
0.65 
0.61 

0.57 
0.48 



cu. 

yd. 



0.40 
0.34 
0.31 
0.27 
0.46 
0.41 

0.37 
0.34 
0.32 
0.29 
0.27 
0.46 
0.42 
0.39 
0.36 
0.34 
0.32 
0.30 
0.52 
0.49 
0.46 
0.43 
0.40 
0.38 
0.36 
0.34 
0.32 
0.51 
0.48 
0.45 

0.42 
0.41 
0.39 

0.37 
0.35 
0.34 
0.55 
0.49 
0.45 
0.42 
0.39 
0.36 
0.42 
0.43 



S I 4J 

2 E 

0) 

U 



0.63 

0.84 
0.95 

1.01 
1.06 
1 



0.60 
0.69 
0.76 
0.82 
0.61 
0.69 
0.75 
0.80 
0.84 
0.87 
0.90 
0.68 

0.74 



0.82 

0.85 

0.88 

0.91 

0.63 
0.68 
0.73 

0.77 
0.80 
0.83 

0.85 
0.89 
0.90 

0.68 
0.72 
0.76 



0.83 
0.87 
0.90 

0.84 
0.85 



bbl. 



3.91 
2.56 
1.90 
1.51 
1.26 
1.07 

0.94 



0.83 



0.75 



0.57 



1.33 
1.23 
1.14 
1.06 
0.99 
0.93 

0.88 
0.84 
0.79 

1 

1.01 

0.94 

0.89 
0.84 
0.80 
0.76 
0.73 
0.69 
0.86 
0.77 
0.70 
0.64 
0.60 
0.55 

0.52 
0.44 



0.38 
0.32 
0.28 
0.25 
0.43 
0.38 
0.35 
0.32 
0.29 

0.27 
0.25 
0.43 
0.39 
0.36 
0.34 
0.31 
0.29 
0.28 
0.49 
0.46 
0.42 
0.39 
0.37 
0.34 
0.83 
0.31 
0.29 

0.48 
0.45 
0.42 



0. 
0, 
0, 

0, 
0. 
0. 

0. 

0. 

0. 

0.38 

0.36 

0.33 

0.38 
0.39 



cu. 
yd 

0.58 
0.76 
0.84 

0.89 
0.93 
0.95 

0.98 
0.98 
1.00 

01 

01 



1 

1 

1.01 

0.56 

0.64 

0.71 

0.76 

0.58 

0.64 

0.69 
0.74 
0.77 

0.80 
0.82 
0.64 

0.68 
0.72 
0.75 

0.78 
0.80 
0.83 

0.59 
0.64 
0.68 

0.71 
0.73 
0.76 
0.78 
0.81 
0.82 

0.64 
0.67 
0.70 
0.72 
0.75 
0.77 
0.79 
0.81 
0.82 

0.64 
0.68 
0.73 

0.76 
0.80 
0.81 

0.77 
0.78 



Note — Variations in the fineness of the sand and the compacting of the concrete may affect the quantities by 
the 10 per cent in either direction. 

* Use 50 per cent columns for broken stone screened to uniform size, t Use 45 per cent columns for average 
conditions and for broken stone with dust screened out. t Use 40 per cent columns for gravel or mixed stone and 
gravel. §Use these columns for scientifically graded mixtures. 



Concrete Reinforcement 



63 



Volume of Concrete Based on a Barrel of 3.5 Cubic Feet 

(See important foot-notes, also page 225) 
(Reprinted by permission from Taylor & Thompson's "Concrete, Plain and Reinforced," page 233) 



Proportions 


by Parts 


Proport 


ions b 


f Volume 


Volume 


Average Volume of Rammed Concrete 
Made from One Barrel of Cement 






of Mortar 
in Terms 
of Percen- 
tage of 


Percentages of Voids in Broken Stone 




i Stone 


Cement 


San 


i Stone 


or Gravel 




Volume 5 




30£§ 


20£§ 




Barrels 


Cubi 
Fee 


c Cubic 
t Feet 


u%* 




*J/'c+ 






C 

I 


ubic 
'eet 


Cubic 
Feet 


Cubic 
Feet 


Cubic 
Feet 


Cubic 
Feet 




1 
2 
3 


1 
1 
1 






3.5 

7.0 

10.5 


101 
54 
39 


5.1 

7.0 


5.3 
7.4 
9.5 


5.5 

7.8 
10.0 


6.0 

8.7 

11.5 


6.4 
9.6 

12.8 






4 
5 
6 


1 

1 

1 






14.0 
17.5 
21.0 


21 
27 

21 


















14.2 
17.0 
19.7 


16.0 
19.2 

22.4 






7 
8 
9 


1 
1 

1 






24.5 
28.0 
31.5 


21 

20 
18 


















.• • 


25.6 
28.8 
32.0 






10 
11 
12 


1 
1 

1 






35.0 
38.5 
42.0 


17 
16 
16 




















35.2 
38.4 
41.6 




1 

1 
1 


IK 
2 

2^ 


1 
1 
1 


3.5 
3.5 
35 


5.2 

7.0 
8.7 


104 
78 
64 


8.0 
8.9 
9.9 


8.3 

93 

10.4 


86 

9.7 

10.8 


9 1 
10 5 
118 


9.7 
11.2 
12.7 




1 
1% 


3 

2 
2K 


1 
1 
1 


35 
52 
5.2 


10.5 
7.0 

8.7 


54 1 
95 1 

78 1 


0.8 
0.2 
1.2 


11.4 
10.6 
11.6 


12.0 
11.0 
12.1 


13 1 
11.7 
13.0 


14.2 
12.5 
14.0 




1% 


3 

3^ 
4 


1 

1 
1 


5.2 
5.2 
5.2 


10.5 

12.2 
14.0 


65 1 
56 1 

50 1 


2.1 
3.0 
4.0 


12 7 
13.7 

14.8 


13.2 

14 4 
15.5 


14.4 
15.7 
17.0 


15.5 

17.0 
18.5 




1% 

iy 2 

2 


4K 

5 

3 


1 
1 
1 


5 2 
52 

70 


15.7 

17.5 
10.5 


45 1 
41 1 

77 1 


4.9 
5.9 
3.4 


15.8 
16.8 
13.9 


16 6 
17.8 
14.5 


18.3 
20.0 
15.6 


20.0 
216 
16 8 




2 
2 

2 


3^ 

4 

4^ 


1 
1 
1 


7.0 
7.0 
7.0 


12.2 
14.0 
15.7 


67 1 
59 1 
53 1 


4.3 
5.3 
6.2 


15.0 
16.0 
17.0 


15.6 
16 8 
17.9 


17.0 

18 3 

19 6 


18.3 
19.8 
21.3 




2 

2. 

2 


5 

5K 

6 


1 
1 
1 


70 
7.0 
7.0 


17.5 
19.2 
21.0 


48 1 
44 1 
41 1 


7.1 
L81 

L9.0 


18.1 
19.1 
20 2 


19.0 
202 
21.3 


20.9 
22 2 
23.6 


22.8 
24.3 

25 8 




2% 
2% 
2/ 2 


3 

4 


1 
1 
1 


8.7 
8.7 
87 


10.5 
12.2 
14.0 


90 ] 

78 ] 
68 1 


14.6 
56 

L6.5 


15.2 
16 2 
17.3 


15.8 
16 9 
18 


16.9 

18.2 
19.6 


18.0 
19.6 
21.1 




2% 
2V 2 
2% 


4K 

5 

5% 


1 
1 

1 


87 

8.7 
87 


15.7 
17.5 
192 


61 ] 
55 ] 
51 ] 


L7.1 
18. 4 
L9.4 


18.3 
19.4 
20 4 


192 
20.3 
21.4 


20.9 
22.2 
23.5 


22.6 
24.1 
25.6 




2V 2 
2V 2 
2% 


6 

7 


1 
1 
1 


87 

87 
8.7 


21.0 
22.7 
24.5 


47 I 
44 I 
41 5 


J0.3 
il.2 

32.2 


21 4 

22 5 
23.5 


22.6 
23.7 

24.8 


24.8 
26.2 
27.5 


27.1 

28.6 
30.1 




3 
3 
3 


4 

4K 
5 


1 
1 

1 


10.5 
10.5 
10.5 


14.0 
15.7 
17.5 


77 ] 
69 ] 
62 ] 


17.8 
18.7 
L9.7 


18.5 
19.6 
20.6 


19.3 
20.4 
21.6 


20.8 
22 1 
23.4 


22.3 
23 8 
25.3 




3 

% 


5K 
6 

6K 


1 

1 
1 


105 
10.5 
10.5 


19.2 
21.0 

22.7 


57 I 
53 J 

49 , I 


JO. 6 
316 
22.5 


21.7 
22.7 
23.7 


22.7 
23.8 
25.0 


24.8 
26.1 
27.4 


26.8 
28.4 
29.9 




3 
3 
3 


7 
8 


1 
1 

1 


10.5 
10.5 
10.5 


24.5 

26.2 
28.0 


46 S 
43 i 

40 I 


33.5 
34.4 
35.3 


24.8 
25.8 
26.9 


26.1 

27 2 
28.4 


28.7 
30 1 
31.4 


31.4 
32.9 
34.4 




4 
4 
4 


5 
6 

7 


1 
1 
1 


14.0 

14.0 
14.0 


17.5 
21 
24.5 


77 j 5 
65 { 
56 i 


32.2 
34.1 
36.0 


23 2 
252 
27.3 


24.1 
26 4 

28.6 


26.0 
28 6 
31.3 


27.9 
30.9 
33 9 




4 
4 
4 


8 
9 

10 


1 

1 

1 


14.0 

14.0 
14.0 


28 
31.5 
35.0 


50 5 
45 i 

41 ; I 


J7.9 

39.8 
51.7 


39.4 
31.5 
33.6 


30.9 
33.2 
35.4 


33.9 
36.6 
39.2 


36.9 
40.0 
43.0 




5 
6 


10 
12 


1 

1 


17 5 
21.0 


35.0 
42 


48 

46 <■ 


54.2 
(0.5 


36.1 

42.8 


38.0 
45.0 


41.8 
49.6 


45.5 
54.1 



Note — Variations in the fineness of the sand and the compacting of the concrete may affect the volumes by 
10 per cent in either direction. 

* Use 50 per cent column for broken stone screened to uniform size, t Use 45 per cent column for average 
conditions and for broken stone with dust screened out. % Use 40 per cent columns for gravel or mixed stone and 
gravel. § Use these columns for scientifically graded mixtures. 



6* 



American Steel and Wire Company 



Volume of Concrete Based on a Barrel of 3.8 Cubic Feet 

(See important foot-notes, also page 225) 
(Reprinted by permission from Taylor & Thompson's "Concrete, Plain and Reinforced," page 234) 



Proportions 


}y Parts 


Proportions by Volume 


Volume 


Average Volume of Rammed Concrete 
Made from One Barrel of Cement 








of Mortar 
in Terms 
of Percen- 
tage of 
Volume 
of Stone 


Percentages of Voids in Broken Stone 
or Gravel 




Sane 


1 Stone 


Cement 


Sand 


Stone 




50%* 


4m 

Cubic 
Feet 


40f4 

Cubic 
Feet 


30^§ 




Cement 


Barrels 


Cubic 
Feet 


Cubic 
Feet 


20^§ 




Cubic 
Feet 


Cubic 
Feet 


Cubic 
Feet 








1 
2 
3 










38 

7.6 

11.4 


94 
51 
36 


5.3 

7.4 


55 

7.8 

10.0 


5.7 

8.2 

1U.6 


6.2 

9.2 

12.2 


6.7 
10 2 
13.6 








4 
5 
6 










15 2 
19 

22.8 


29 
25 

22 












15.2 
18 2 
21.1 


171 
20.6 
21.0 








7 
8 
9 










26 6 
30.4 
34.2 


20 
19 

18 
















27.5 
31.0 
34.4 








10 
11 
12 










38.0 
41.8 
45.5 


17 
16 
15 
















37.9 
41.4 

44.8 




1 
1 

1 


IK 

2 

2% 




38 
38 
3.8 


5.7 
7.6 
9.5 


99 
75 
61 


8.5 

95 

10.5 


88 

9.9 

10.0 


91 
10.3 
11.5 


9.7 
11.1 
12.6 


10.3 
11.9 
13.6 




1 

VA 

1% 


3 

2 
2% 




38 
5.7 
5.7 


11.4 
7.6 
9.5 


51 
93 
76 


11.5 
10 8 
11.9 


12 2 
11.3 
12.4 


12.8 
11.7 
12.9 


14 
12.5 
13.9 


15.2 
13.3 
15.0 




l l A 

i l A 


3 

3K 
4 




57 
5.7 
5.7 


11.4 
13.3 
15 2 


64 
55 

49 


12 9 
13.9 
15.0 


13 5 

14 6 
15.8 


14.1 
15 4 
16.6 


15.4 
16 8 
18.2 


16.6 
18 2 
19.9 




v/ 2 

2 


4K 

5 

3 




5.7 
5.7 
7.6 


17.1 
19.0 
11.4 


41 
40 
75 


16 

17 
14.3 


16 9 
18 
14.9 


17.8 
19 1 
15.5 


19.7 
21 1 
16.7 


215 
23 2 
18.0 




2 
2 
2 


3K 
4 

4K 




7.6 
76 
7.0 


13 3 
15.2 
17 1 


65 
57 
51 


15 3 

16.3 
17.4 


16.0 
17.2 
18.3 


16.8 
18.0 
19.2 


18.2 
19.6 
21 


19.6 
21.3 

22 9 




2 
2 
2 


5 

5 l A 
6 




7.6 
7.6 
7.6 


19.0 
20 9 

22.8 


47 
43 
40 


18.4 
19.4 
20.4 


19.4 
20.5 
21.7 


20 4 
21.7 
22 9 


22.5 
23.9 
25.4 


24.5 
26 2 

2?.8 




2% 
2% 
2 l A 


3 

sy 2 

4 




9.5 
9.5 
9.5 


11.4 
133 
15 2 


87 
75 
66 


15 7 

16 7 
17.7 


16 3 
17.4 

18.5 


16 9 
18 1 
19.3 


18.1 
19 6 
210 


19.3 
21 

22.6 




2\4 
2% 
2% 


4K 
5 

5K 




95 
9.5 
95 


17 1 
19.0 
20.9 


60 
54 
49 


18.7 
19.8 
20.8 


19.6 

20.8 
21.9 


20.6 
21.8 
23.0 


22.4 
23.9 
25 3 


24.3 
25 9 
27.6 




2V 2 
2V 2 
2% 


6 

6K 

7 




9.5 
95 
95 


22.8 
24.7 
26.6 


46 
42 
40 


21.8 
22 8 
23.9 


23 

24 2 
25.3 


24.3 
25.5 
26 7 


26.7 
28.2 
29.6 


29.2 
30.8 
32.5 




3 
3 
3 


4 

4^ 

5 




11.4 
114 
114 


15.2 
17.1 
19.0 


76 
68 
61 


19 1 

20 1 
21.1 


19.9 
210 
22.1 


20.7 
21.9 
23.2 


22 4 

23 8 
25 2 


24.0 
25 6 
27.2 




3 
3 
3 


5K 

6 

6K 




11 4 
11.4 
11.4 


20.9 
22.8 
24.7 


56 
52 

48 


22 1 

23 2 

24 2 


23.3 
21.4 
25 5 


24.4 
25 6 
26.9 


26 7 
28.1 
29.5 


28 9 
b0 6 
32 2 




3 
3 
3 


7 

7K 
8 




11 4 
114 
11.4 


26.6 
28.5 
30.4 


45 
42 

40 


25 2 
20.2 
27.8 


26 7 
27.8 
28 9 


28.1 
29 3 
30.6 


31.0 
32.4 
33.8 


33.8 
35.5 
37.3 




4 

4 

4 


5 

G 

7 




15.2 
15.2 
15.2 


19.0 
22.8 
26.6 


76 
64 
55 


23.9 
25.9 

28.0 


24 9 

27.2 
29.4 


25 9 

28.4 
30.8 


28 
30.8 
33.7 


30.0 
33.3 
36.6 




4 
4 
4 


8 

9 

10 




15 2 
15.2 
152 


30.4 
34.2 
38.0 


49 

44 
40 


30.0 
32.1 
34.1 


31.7 
33 9 
36.2 


33.3 

35 8 
38.2 


36 6 
39.4 
42 3 


39.9 
43.1 
46.4 




5 



10 
12 




19.0 

22.8 


38.0 
45 5 


47 
46 


36.9 
43.7 


38.9 
46 2 


41.0 
48.6 


45.1 
53.6 


49 2 
58 5 



Note — Variations in the fineness of the sand and the compacting of the concrete may affect the volumes by 
10 per cent in either direction. 

* Use 50 per cent column for broken stone screened to uniform size, t Use 45 per cent column for average 
conditions and for broken stone with dust screened out. % Use 40 per cent column for gravel or mixed stone and 
gravel. § Use these columns for scientifically graded mixtures. 



Concrete Reinforcement 



65 



Volume of Concrete Based on a Barrel of 4 Cubic Feet 

(See important foot-notes, also page 225) 
(Reprinted by permission from Taylor & Thompson's " Concrete, Plain and Reinforced," page 235) 



Proportions 


oy Parts 


Proport 


ions by Volume 


Volume 


Average Volume of Rammed Concrete 
Made from One Barrel of Cement 






of Mortar 
in Terms 
of Percen- 


Percentages of Voids in Broken Stone 














or Gravel 




San 


I Stone 


Cement 


Sand 


Stone 


tage of 




Cement 


Volume 5 
of Stone 


Q%* 


45f4 


4Q%i 


302§ 


20£§ 


Barrels 


Cubic 
Feet 


Cubic 
Feet 






C 
I 


ubic 
"eet 


Cubic 
Feet 


Cubic 
Feet 


Cubic 
Feet 


Cubic 
Feet 








1 
2 
3 








4 

8 
12 


89 
49 
35 


54 

76 


5.6 

8.0 

10 4 


5.8 

8 4 

11.0 


6.4 

95 

12 7 


6.9 
10.5 
14 2 








4 
5 
6 








16 
20 
24 


28 
24 
22 












15.8 
18.9 
22 1 


17.8 
215 
25 1 








7 
8 
9 








28 
32 
36 


20 
18 

17 














28.8 
32.4 
36.1 








10 
11 

12 








40 
44 
48 


16 
15 
15 














39 7 
43.4 
47.0 




1 
1 
1 


IK 

2 
2K 




4 
4 
4 


6 

8 
10 


96 
73 
59 1 


88 
98 
09 


91 
10 3 
11.5 


9.4 
10.7 
12.0 


10 
11.6 
13.1 


10.7 
12.4 
14 2 




1 

IK 


3 

2 
2K 




4 

6 
6 


12 

8 
10 


50 1 
92 1 
74 1 


2.0 
1.3 
24 


12.7 
117 

12 9 


13.3 
12.2 
13.5 


14 6 

13 

14 5 


15 9 
13 9 
15.6 




iK 

ik 


3 

3K 

4 




6 
6 
6 


12 

14 
16 


62 1 
54 1 

48 1 


35 
4.5 
5.6 


14 1 

15 3 

16 5 


14 8 

16 

17 3 


16.0 
17.6 
19.1 


17 3 

19.1 

20.8 




IK 

jk 

2 


4K 

5 

3 




6 
6 

8 


18 
20 
12 


43 1 
L9 1 

74 1 


67 
78 
4.9 


17 7 
18.9 
15.6 


18.6 
19 9 
16.2 


20 6 
22.1 
17.5 


22.5 
243 

18.8 




2 
2 
2 


3^ 

4 

4K 




8 
8 

8 


14 

16 

18 


64 1 
56 1 
51 1 


6.0 
7.1 

81 


16.7 

17 9 
19.1 


17 5 
18.8 
20.1 


19.0 

20 5 
22.0 


20 5 
22.3 
23.9 




2 
2 
2 


5 

5K 
6 




8 
8 
8 


20 
22 
24 


46 1 
42 £ 
39 £ 


9.2 
!0.3 
•1.4 


20.3 
21.5 
22.7 


21 4 
22.7 
24.0 


23 5 
25 1 
26.6 


25 7 
27.4 
29.2 




2% 

2%. 
2% 


3 

3^ 
4 




10 
10 
10 


12 
14 
16 


86 1 
75 1 
66 1 


6.3 

7.4 

8.5 


17 
18.2 
19 4 


17 6 

18.9 
20.2 


18.9 
20.5 
21.9 


20.2 
22.0 
23.7 




2% 
2% 
2% 


4K 
5 

5K 




10 
10 

10 


18 
20 

22 


50 1 
54 £ 
49 £ 


9.6 
07 

18 


20 6 

21 8 

22 9 


21.5 

22.8 
24.1 


23 5 

25 
26.5 


25 4 

27.2 
28 9 




2K 

2K 

2% 


6 
6K 

7 




10 
10 
10 


24 
26 

28 


45 £ 
42 2 
39 £ 


28 
3.9 
5.0 


241 
25.3 
26.5 


25.4 
26 7 
28.0 


28.0 
29 5 
31.0 


30 6 
32 3 
34.0 




3 
3 
3 


4 

5 




12 
12 
12 


16 

18 
20 


75 £ 
67 £ 
60 £ 


00 
1.0 
2.1 


20 8 

22 

23 2 


21.7 
23.0 
24.3 


23.4 
24.9 
26 4 


25.1 

26.8 
28.6 




3 
3 
3 


5K 

6 

6K 




12 
12 

12 


22 
24 
26 


55 £ 
50 £ 
48 £ 


3 2 
4.3 

5.4 


24 4 

25 6 

26.8 


25.6 
26.9 

28.2 


28.0 
29.5 
31.0 


30.3 
32.1 
33.8 




3 
3 
3 


7 
7K 

8 




12 
12 
12 


28 
30 
32 


44 £ 
42 £ 
39 £ 


6.4 
7.5 

86 


27 9 
29.1 
30 3 


29 4 
30.8 
32.0 


32 5 
34.0 
35.5 


35.5 
37 2 
39 




4 
4 
4 


5 

6 

7 




10 
16 
16 


2D 
21 

28 


75 £ 
63 £ 
55 2 


50 
72 
93 


26.1 

28 5 
30.8 


27.2 
29.8 
32.4 


29 3 
32 4 
35.4 


31.5 
35.0 
38.4 




4 
4 
4 


8 

9 

10 




16 
16 
16 


32 
36 

40 


48 3 
83 3 
48 3 


15 
3.6 
5.8 


33.2 
35.6 
38.0 


34.9 
37 5 
40.1 


38.4 
41 4 
44 4 


41.9 
45.3 

48.8 




5 

6 


10 
12 




20 
24 


40 
48 


47 3 
46 4 


S.7 
59 


40.9 

48.5 


43.0 
51.1 


47.3 
563 


51.7 
61.4 



Note — Variations in the fineness of the sand and the compacting of the concrete may affect the volumes by 
10 per cent in either direction. 

* Use 50 per cent column for broken stone screened to uniform size, t Use 45 per cent column for average 
conditions and for broken stone with dust screened out. $ Use 40 per cent columns for gravel or mixed stone and 
gravel. § Use these columns for scientifically graded mixtures. 



66 



American Steel and Wire Company 



Theory of Reinforced Concrete 

It is not our intention to give here a complete mathematical analysis of the 
stresses which occur in reinforced concrete structures. For such an analysis 
we would refer to any of the standard text books on the theory of reinforced 
concrete, where the subject is treated to a much larger scale than would be 
possible in the scope of this book. 

The following formulas are now recommended by practically all the best 
authorities on reinforced concrete. They are based on the " straight line," or 
linear distribution of stress : 



Notation 

f = unit fiber stress in steel in pounds per square inch. 

f = unit fiber stress in concrete, extreme fiber in compression. 

E = modulus of elasticity of the steel. 

E = modulus of elasticity of the concrete. 

E 9 
n = ratio — 




M = resisting moment in inch pounds due to steel. 

M = resisting moment in inch pounds due to concrete. 

b = breadth in inches of rectangular beam. 

d = depth in inches of center of steel from compression 
face of concrete. 

k = ratio of depth of neutral axis below the top to the 
effective depth d. 

j = ratio of arm of resisting couple to depth d. 



A = area in square inches of cross section of steel, 
p = steel ratio (not per cent) — 

The position of the neutral axis is shown by the formula 

K = 1 / 2pn + (pn) a — pn 

The lever arm of the resisting couple is shown by 

Resisting moment as governed by the steel, 

M 8 = f 8 pjbd 2 
Resisting moment as governed by the concrete, 

m c = y 2 f c kjbd* 

For approximate results use the average values, k : 

m =#dAf ...(i; 



Y% and j = j£, which gives 



M 



ibd*f...(2) 



Both moments should be figured and the lesser one used. 



Concrete Reinforcement 67 



Tee-beams 

The same formulas hold good for the tee-beams except that the breadth (b) 
of the beam is in this case the width of the flange and not the width of the stem. 
Where tee-beams are formed by casting the rectangular beams monolithic with 
the floor slab, the resisting moment will in ordinary construction depend on 
the resistance of the steel in tension, so that it will only be necessary to use the 
formula for (M s ) in order to determine the resisting moment of the section. 



Bending Moments 

If slabs and girders be reinforced to take care of negative bending moments 
over supports, they will act as continuous beams, and the bending moment at 
the center of the span will be reduced. It is considered good practice to use 
the following values : 

For beams and slabs continuous over both supports, 

Continuous over one support only, 

M = T V wl 2 

Freely supported, 

M = iwl 2 

When M = bending moment at center of span in foot pounds. 

w = total uniform live and dead load in pounds per square foot. 

1 = length of span in feet. When these moments are substituted in equation (1) and 
(2) they are to be multiplied by 12 to reduce the moment to inch pounds. 

Unless care be taken to insure proper position of steel over supports, we would 
recommend using M = -^wl 2 . 



Shear in Rectangular Beams 

Let V — total shear at the sections in pounds, 
b — width of section in inches. 
d = depth of section to center of steel in inches, 
v = unit shear in pounds per square inch. 

V 

then v i= — - 
bd 

With beams having no web reinforcement the working stresses should not 
exceed 35 to 40 pounds per square inch of cross section area of the concrete 
above the plane of the horizontal steel. If the beam has sufficient web rein- 
forcement the working stresses may be taken at 100 to 125 pounds per square 
inch. 

The web reinforcement may be supplied by using either vertical or 
inclined stirrups, or by bending up a portion of the main tension bars, or both 



68 



American Steel and Wire Company 




7riangfe Mesh 
fabric 






combined. By using triangle mesh wire 
fabric in the form of a cage, as shown 
by the accompanying cut, the cross wires 
will give sufficient web reinforcement 
for all ordinary cases. By referring to 
the tables on pages 110 and 111 it is 
seen that these cross wires may be either 
No. 14 or No. 12^4 gage spaced either 
2 or 4 inches apart, thus giving a varia- 
tion in amount of web reinforcement. 
This material, having a joint at each 
longitudinal, can be placed in forms at a very small expense as compared with 
loose stirrups. Another point in favor of triangle mesh fabric for web 
reinforcement is the truss action which this material ^ives, thus adding 
another factor of safety to the structure. 

In cases of tee-beams it is necessary that the web reinforcement be carried 
well up into the slab to prevent shearing off on a plane between the flange and 
stem. 



Beam 5ectron 



Concrete Reinforcement 69 



Explanation of Tables for Reinforced Concrete Slabs 

(Pages 74-86) 

The following tables are based on the "straight line" formula, or linear 
distribution of stress as shown on page GG. The ratio of the modulus of 
elasticity of steel to concrete is taken as fifteen. Values of resisting moments 
of slabs are given per foot of width for various maximum values for steel and 
concrete. Below and to the left of the heavy zigzag line, values of resisting 
moments are given as governed by the maximum allowable fiber stress in steel; 
the values above and to the right of this line are governed by maximum allow- 
able fiber stress in concrete. The various values for maximum fiber stresses 
are thus given so that almost any specifications may be complied with. 

The tables have been arranged in such a manner that a uniform reinforce- 
ment may be used and by increasing or decreasing the thickness of the slabs, 
spans of greater or less length than the average spans of the floor may be taken 
care of economically with the same reinforcement. 

The second column gives the distance in inches from the center of the steel 

to the bottom of the slab. The third column gives the weight of the concrete 

slab per square foot of floor area, this weight being based on concrete weighing 

144 pounds per cubic foot. Although in the following examples we have used 

Wl 2 . . Wl 2 
the formula B. M. =-— , it is considered good practice to use B. M. = 

when the slab is continuous over both supports ; however, care must be taken 
to have the reinforcement near the top of the slab over supports in order to 
resist the negative bending moments at these points : 

Examples of the use of these tables : 

Given : A live load of 75 pounds per square foot ; span of slab, 8 feet ; floor, cement 
finish of slab, no plaster below ; maximum allowable fiber stress in steel, 18,000 pounds per 
square inch ; maximum allowable fiber stress in concrete, 650 pounds per square inch. 

Look in the Table No. 13 giving minimum thickness of slabs for various 
spans. From this table we find for a load of 100 pounds per square foot and 
span of 8 feet, a minimum thickness of 3^2 inches is recommended, It is 
better, however, to make this slab 4 inches thick. 

The total dead load consists of the 4-inch slab, which will weigh 

48 pounds per square foot. 

Live loads 75 pounds per square foot. 

Total 123 pounds per square foot. 



70 American Steel and Wire Company 

For slabs continuous over supports, figure the bending moment as follows 
(or use diagrams No. 1 or No. 2, pages 88 and 89). 

Bending moment in foot pounds is equal to the total load per square foot 

multiplied by the span of the slab (in feet) squared and divided by ten. Or 

expressed as a formula (see article on bending moments, page 67). 

wl 2 
B.M.=- 

In which 

B. M. = Bending moment in foot pounds. 

w = Total load in pounds per square foot. 
1 = Length of span in feet. 

For this particular example 

w — 123 (pounds per square foot). 
1 = 8 (feet span of slab). 
Then 

l°3x8 2 
B. M. = ^— — = 787 foot pounds. 

Now it is necessary to find in Table No. 7 (corresponding to the given 
allowable stresses) the reinforcement for a 4-inch slab that will resist a bending 
moment of 787 foot pounds. 

In this table we find a cross sectional area of steel of 0.18 square inch 
per foot width of slab will be needed to make a 4-inch slab capable of resisting 
a bending moment of this amount. 

This area will be supplied with our Triangle Mesh Reinforcement style num- 
ber (33) as shown in the next to the last column in the tables page 110; or the slab 
thickness can be changed back to Sj4 inches, in which case approximately 0.22 
square inch will be required (exact amount may be determined by deducting 
6 pounds from the total load and again determining the B. M.). Style No. 32 
having a cross sectional area of . 225 square inch per foot width will give 
the necessary steel area. 



Slabs Reinforced in Two Directions 

It is very often desirable to reinforce the floor slab in two directions, and 
support the slab by means of beams (or walls) on four sides. If the panel is 
square then one-half of the total load is carried in each direction. In this case 
the bending moment due to the total load will be : 

B. M. =-L X w X P 

Example : 

Given : A live load of 75 pounds per square foot ; size of panel 12 x 12 feet ; floor, 
cement finish of slab ; maximum allowable fiber stress in steel, 18,000 pounds per square inch; 

wl 2 

fiber stress in concrete, 650 pounds per square inch ; bending moment =-— -. 



Concrete Reinforcement 



71 



We will assume a 4-inch slab. In this example w = live load of 75 pounds plus 

weight of a 4-inch slab or 48 pounds, giving a total load of 123 pounds per square foot ; 

12S V M2^ 2 
(1) = 12 feet, therefore B. M. = ^ K ' = 886 foot pounds. 

Now, referring to Table No. 7, in order to find the reinforcement for a 4- 
inch slab that will resist a bending moment of 886 foot pounds, we find a cross 
sectional area of steel of 0.205 square inch per foot width of slab will be 
needed to make a 4-inch slab capable of resisting a bending moment of 886 
foot pounds. This area will be supplied with our Triangle Mesh Reinforce- 
ment, style No. 41 (see page 110) one layer placed in each direction. 



Panels having Greater Length than Breadth 

The distribution of load is first determined by the formula 

14 
r ~ l*+b* 

in which r equals proportion of load carried by the reinforcement placed the 

short way of the slab, 1 = length and b = breadth of slab. 

length 
The following diagram shows the value of r for various ratios of j- — ^-— 




■ ■rjr. ( Mwi,WMmmriUinwr.»:mmrir,immT,rimmrir*mmT,udMMr,-'MU*r,'.^mi7rj,-mmMu 
■■■■■ "ill I' ''.imm n ,mmm /' «■■ ffinu tm*nun'aw*£:miv*ww * 'mmw*~Mmr*,'MMmma 



23 



^SS 



iVnViil& 



:^: 



vM^iivdi&w. 



M 



mvi 



!l 



Rectangular Slabs 



72 American Steel and Wire Company 

Example : 

Given : A live load of 75 pounds per square foot ; size of panel 12 x 10 feet ; floor, 
cement finish of slab ; maximum allowable fiber stress in steel 18,000 pounds per square 
inch ; maximum allowable fiber stress in concrete 650 pounds per square inch. 

In this example we will assume a 4-inch slab, then w = 75 pounds live load plus weight 
of a 4-inch slab or 48 pounds, giving a total load of 123 pounds per square foot. 

Now, to determine what portions of this load are carried by the two systems of rein- 
forcement, divide the length of panel by breadth, or 

JL_i?_l » 

b ~ 10 - 

Now, with this value for — we will enter the diagram for rectangular slabs (page 71). 
"We find the value of — z= 1 . 2 and follow the vertical line to the point of its intersection 

with the curved line ; now following the horizontal line to the left we find that — — of the 

total load is carried by the short span reinforcement ; then necessarily the remaining part or 

33 

■ of the total load is carried by the lone: span reinforcement. The two systems of rein- 

100 

forcement are now treated as separate problems. 

The bending moment for the short span = B. M. = — X load X span squared. 

67 
But load = — X 1'23 pounds = 83 pounds per square foot ; therefore B. M. == 

83 X 1Q2 = 830 foot pounds. 
10 

Referring to Table No. 7 to find the reinforcement for a 4-inch slab that will resist a 

B. M. of 830 foot pounds, we find a cross sectional area of steel of 0.19 square inch per 

foot width of slab will be needed to make a 4-inch slab capable of resisting a bending moment 

of 830 foot pounds. This can be supplied by our style No. 33. (See page 110.) 

The bending moment for the long span = 

1 °3 

B. M. = -jr- X load X span squared. But load = ^— - X 123 = 40 pounds per square 



foot 



40 X 12 2 
Therefore B. M. = — ^- = 576 foot pounds. 



Concrete Reinforcement 73 



Again referring to Table No. 7 we find a cross sectional area of steel of 
0.125 square inch per foot width will be needed to make a 4-inch slab 
capable of resisting a bending moment of 576 foot pounds. This can be 
supplied by our style No. 25. (See page 110.) 

Note — When a sectional area of steel is required which is greater than can 
be supplied by one layer of our heaviest material, either use two layers of 
fabric or one layer of fabric with a sufficient number of loose bars to make up 
the required area. 



74 



American Steel and Wire Company 



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Concrete Reinforcement 



87 












^-/Pe/n fore em enf 






3B3»v4 ^7?v<p /avers or" /fe/nforcemenr V^-'-tr 

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88 



American Steel and Wire Company 




Diagram No. 1. Bending Moments for Slabs and Panels 



Concrete Reinforcement 



89 




Diagram No. 2. Bending Moments for Slabs and Panels 



90 American Steel and Wire Company 

Reinforced Concrete Columns 

Vertical reinforcement is used in concrete columns in order to carry a 
portion of the direct compressive stresses and also to take care of bending 
stresses due to eccentric loading on the columns. 

If bars are used, it is necessary to band or tie them together. These 
bands should be so spaced that the unsupported length of the rods between 
bands is not too great to permit of column action. 

The column sketches on page 91 show how Triangle Mesh Wire 
Fabric is used in column construction. The fabric is constructed with a 
joint at each longitudinal so that the column cages may be formed without 
bending the wires. The cross wires act as bands holding the longitudinal 
members in place and also add a factor of safety to the construction by reason 
of their " hoop " action. If it is necessary to have a greater section of vertical 
steel, place bars inside of the wire fabric. 

The size of column and amount of reinforcement necessary to carry a 
given load may be determined by means of the formula : 
P = A f + nf A 

C C C 8 

Where P = Load on column in pounds. 

A = Cross sectional area of concrete, square inches. 
A = Cross sectional area of steel, square inches. 
{ = Allowable stress in concrete in compression, pounds per square inch. 

Modulus of elasticity of steel 
n = ratio, 



Modulus of elasticity of concrete 



The following diagrams, pages 92 and 93, for Safe Loads on Square and 
Round Columns are based on a value of 15 for n and 600 pounds per square 
inch for f c . They show the amount of vertical reinforcement required in order 
that a column of given size will carry the given load. An examination of 
these diagrams shows that with a given load, the size of column may be varied 
by varying the amount of vertical reinforcement. 



Concrete Reinforcement 



91 





Triangle Mesh Reinforcement is most applicable to columns for hoop 
reinforcement, due to the hinge joint provided at each longitudinal member, 
thus allowing the material to be readily folded without bending the wires. It 
may be used for either round or square columns of various diameters, due to 
the number of different widths in which Triangle Mesh Reinforcement is 
made. The accompanying illustrations demonstrate its adaptability for 
column work. Additional bars may be included for vertical reinforcement if 
so desired. 



92 



American Steel and Wire Company 




Safe Loads and Area in Square Indies of Steel for Square Columns 



Concrete Reinforcement 



93 




Safe Loads and Area in Square Inches of Steel for Bound .Columns 



94 American Steel and Wire Company 



Mechanics of Pipes and Rings Subject to External 

Pressure 

Note — Through the courtesy extended by Arthur N. Talbot, University 
of Illinois, we reprint the following extracts from their Bulletin No. 22 dated 
April 29, 1908, on reinforced concrete culvert pipe, sewer pipe, etc. 

Bending Moment and Conditions of Loading 

The stresses developed in rings subject to external earth pressure, as in 
sewers and railroad culvert pipes, are of course dependent upon the bending 
moments developed, and as the exact load coming upon the ring and its dis- 
tribution over the surface are difficult to determine, the bending moment is in 
general quite uncertain. The amount of the load and its distribution, and 
therefore the bending moments on different parts of the ring depend upon a 
number of conditions, among them the nature of the earth used in the filling, 
the method of bedding the pipe, the way of tamping the earth at the sides, 
the amount of lateral restraint or pressure of the earth horizontally, the 
method of filling and packing the earth above, the condition of moisture in 
the earth, etc. Evidently in such earth as saturated quick-sand, the con- 
ditions may approach those of external hydrostatic pressure, and on the other 
hand, in deep sewer trenches, the earth filling may act in such a way that 
much of its weight is carried against the sides of the trench. In discussing 
the stresses in rings, it may be well first to find the bending moment for 
certain assumed conditions of loading, then to make tests under various con- 
ditions of loading, and finally to compare these results with a view of deter- 
mining the probable range of bending moments under the actual conditions 
of construction. The assumed loadings may include (1) a concentrated load 
at the crown of the ring, (2) a vertical load distributed uniformly over the 
horizontal section (3) a distributed vertical load together with a horizontal 
load distributed vertically over the sides of the ring, and (4) an oblique load- 
ing. In these calculations, since much uncertainty is involved, the difference 
in the intensity of the load at the crown and at the extremities of the horizontal 
diameter j due to the different depths of earth, need not be considered. In 
general the pressures and distribution on the lower half of the ring will be 
considered to be the same as on the upper half. It is apparent that in a ring 
of considerable thickness in comparison with its diameter there is a different 
distribution of stresses from that found in thin rings, but for the rings under 
consideration the simplicity of analysis for thin rings will outweigh the small 
loss in accuracy. The possible modifications and complications in the analysis 
of thick rings may also be considered. As refinements are not essential and 
approximations are permissible, the analysis will assume a thin ring of homo- 
geneous material having a constant modulus of elasticity and it will also be 
assumed that the changes from a circular form will have little effect upon the 
dimensions of the ring. 



Concrete Reinforcement 



95 



Concentrated Vertical Load on Thin Elastic Ring 

Consider that a concentrated load Q is applied along the top element of 
a cylindrical ring and that the ring is supported along an element at the 
bottom, as indicated in Fig. 1 (a). Since the ring is a continuous curved 
beam, the analysis will require a slight modification of the convention com- 
monly used for simple straight beams. However, in any segment of the ring, 
the external forces acting on the ring will be held in equilibrium by the internal 
or resisting forces acting upon this segment at its two ends. The moment of 
the internal forces acting at right angles to a section of the ring at an end of the 
segment is the resisting moment developed, and the bending moment may be 
considered to be an equal moment having the opposite sign. If we take a 
quadrant of the ring, as shown in Fig. 1 (b), it is evident from a consideration 
of the external and internal forces acting upon this ring that this quadrant 
will be in equilibrium under the action of ^Q at B, a reaction or thrust of 
j4Q at A, a resisting moment in the section of the ring at A, which we will 
call M A , and a resisting moment in the section of the ring at B, which we 
will call M B . The amounts of the two resisting moments so developed and 
thus of the two bending moments it is important to determine. Similarly, if 
we consider a portion of the ring shown in Fig. 1 (c), the forces which hold it 




(a) 




(i?> (c) 

Fig. 1. Ring under Concentrated Load 



(cf> 



in equilibrium may be shown to be ^ Q at A, %Q_ at C, the moment M A at 
the section A, and a variable moment M at C, the value of which will change 
with a change in the angle (p. Taking moments about A, the following 
equation for the value of the bending moment at any point on the ring results 
M = ^Qr (1— cos0) — M a . .... .(1) 

1 



♦but, M A = -51 (1 



Yz 7t 



) = .091 Qd 



(4) 



where d is the mean diameter of the ring. 

* See Bulletin No. 22, University of Illinois, for full mathematical proof. 



96 



American Steel and Wire Company 



Substituting this value of M K in equation (1) and making <f= 90°, we 



have 



M = ^ — .091 Qd = .109 Qd 
b 4 



(5) 



It will be seen that the bending moment at B is about sixteen-ninths times that 
at A. 





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Ftg. Z. Variation in Bending Moment For Concentrated /.oaa/. 

To determine the point of zero bending moment place equation (1) equal 
to zero, cos = .(336 and = 50° 30'. At this point the algebraic sign of 
the bending moment changes from negative to positive. 

Fig. 2 gives the variation of the bending moment from A to B. 

It may be shown that if the load be applied equally at two points on 
either side of the crown (and similarly supported below) the bending moment 
at the crown will be decreased and that if these points are immediately above 
the quarter points of the diameter the value of the bending moment at the 
crown becomes 0.054 Qd and that at the extremities of the horizontal diameter 
0.071 Qd. This has a bearing upon the effect of the methods of bedding 
a pipe. 

Distributed Vertical Load on Thin Elastic Ring 

Consider that the vertical load is distributed uniformly over the hori- 
zontal projection of the ring, as shown in Fig. 3 (a), and call w the load 
per lineal unit of horizontal width for a ring one unit long and r the mean 
radius of the ring. 

The expression for the bending moment M at any point C on the ring is 
found by taking moments about C. 



Concrete Reinforcement 



97 



M = wr 2 (1 cos (p)— l / 2 wr 2 (1 — cos 0) 2 — M A 
= l / 2 wr 2 (1 — cos 2 0) — M a . . . . . (6) 




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where d is the mean diameter of the ring and W is the total load on a 
ring of unit length. 































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Fig. 4. Variation ir? Bending moment for distributee/ load. 

• See Bulletin No. 22, University of Illinois, for full mathematical proof. 



98 



American Steel and Wire Company 



Distributed Vertical and Horizontal Loads on Thin Elastic Ring 

Let us consider that the vertical load is distributed over the horizontal 
section of the pipe as before (w per lineal unit of width of pipe) and that 
there is a horizontal pressure uniformly distributed vertically against the pipe, 
the amount of this horizontal pressure per lineal unit of vertical distance being 
q\v, where q is the ratio of the horizontal to the vertical intensity of pressure. 
The conditions are indicated in Fig. 5 (a). We may consider that the effect 
of these loads is the combined effect of the two loads. Call M', M' A and 
M' B the bending moments produced by the vertical load and M", M" A and 
M" B the bending moments produced by the horizontal load. The bending 
moment at any section C (Fig. 5 (b) ) produced by the vertical load is 

M' = wr 2 (1 — cos (p) — % wr 2 (I — cos 0) 2 — M' . 




M U>) (c) 

Fig. 5. Ring Under Distributed Vertical and Horizontal Load 

It may be shown that the bending moment produced at any section C by the 

horizontal load is 

M" = — y 2 qwr 2 sin 2 + M" a 

and that the value of M" A is ^ qwr 2 . The resulting moment therefore is 

M = M' + M" — X ^" r2 [1 + q — 2 cos 2 — 2q sin 2 0] . . . (8) 
The moment at B and A will therefore be 

M b = - M A = X (1 - q) wr* = ^ (1 - q) Wd ... (9) 
where W is the total vertical load on the ring. The bending moment becomes 
zero at = 45° as in the other case. 

If the intensity of the horizontal pressure is the same as that of the vertical 
pressure, q = 1 and M becomes zero at all points. This corresponds to 
uniform external pressure as shown in Fig. 5 (c) and produces equal compres- 
sion in all parts of the ring. 

Resisting Moment and Calculation of Stresses 

For a ring whose thickness is small in comparison with the diameter, the 
difference in length of the inner fiber and outer fiber is small and the expres- 



Concrete Reinforcement 99 



sion for the resisting moment given for ordinary straight beams may be applied 
with a close degree of approximation. 

For a ring made of reinforced concrete the conditions differ somewhat 
from those of a homogeneous elastic material. For ordinary cases it will be not 
far from the truth to equate the bending moment determined as above and the 
resisting moment of the reinforced concrete section. As the amount of rein- 
forcement is usually lower than that in which the circular beam would fail by 
compression in the concrete, we may, without material error, take for the 
resisting moment of the reinforced concrete section the value .87 Aft, where 
(t) is the distance from the compression face to the center of the steel reinforce- 
ment, A is the area of the cross section of the reinforcement for a unit of length 
of ring, and f is the tensile unit stress in the steel due to the bending moment. 
To equate the bending moment determined as before to this resisting moment 
is not exactly correct, since among other reasons the neutral axis does not 
come at the center of the thickness of the ring (which is the point about which 
the bending moments were taken), and since the elastic curve is not the same 
as in a ring of homogeneous material, and hence the distribution and amounts 
of the bending moments will not be exactly the same. However, the use of 
the bending moments determined for homogeneous rings is the nearest approxi- 
mation we have, and is not seriously in error. At sections where thrust occurs, 
as at A (figure 3), the tension in the steel determined as above will be reduced 
by the resisting compressive stresses there set up. The amount of the tension 
in the steel at the point A may be calculated by the formula 

%^__ (19) 

t(l + np) 

which is applicable for both concentrated and distributed loads. In this formula 
f is the tensile stress in the steel due to the bending moment (as calculated by 
equating .87 Aft to the bending moment at the section considered), p is the 
ratio of the area of reinforcement for a unit length of beam or ring to the 
distance between the center of the steel and the compression face of the con- 
crete, T is the thrust or pressure against the face of the section, and n is the 
ratio of the moduli of elasticity of steel and concrete, which, for purposes of 
this calculation, may be taken as 15. At the extremity of the horizontal 
diameter the thrust is Y /z W. At the crown it is zero for vertical loading, and 
for both concentrated and distributed load the greatest tensile stress is found 
at this section. 

Conditions of Bedding and Loading Found in Practice 

The foregoing discussion assumes certain definite conditions of loading. 
These are useful in establishing definite formulas which may be used as a 
basis for calculations. It is not to be expected that these conditions represent 
accurately the condition of bedding and loading to be found in practice. It is 
then desirable that the nature and extent of possible or probable variations 



100 American Steel and Wire Company 

from these assumed conditions be discussed and the effects of such a divergence 
considered. The following are suggestions of variations; the engineer will 
easily extend the discussion by numerous examples taken from his own 
experience. 

If the layer of earth immediately under the pipe is hard or uneven, or if 
the bedding of the pipe at either side is soft material or not well tamped, the 
main bearing of the pipe may be along an element at the bottom and the result 
is in effect concentrated loading. The result is to greatly increase .the bending 
moment developed and hence the tendency of the pipe to fail. This condition 
may be aggravated in the case of a pipe with a stiff hub or bell where settle- 
ment may bring an unusual proportion of the bearing at the bell and the dis- 
tribution of the pressure be far from the assumed condition. In bedding the 
pipe in hard ground, it is much better to form the trench so that the pipe will 
surely be free along the bottom element, even after settlement occurs, and so 
that the bearing pressures may tend to concentrate at points say under the 
one-third points of the horizontal diameter (or even the outer quarter points). 
This will reduce the bending moments developed in the ring. 

In case the pipe is bedded in loose material, the effect of the settlement 
will be to compress the earth immediately under the bottom of the pipe more 
completely than will be the effect at one side, with the result that the pressure 
will not be uniformly distributed horizontally. Similarly, in a sewer trench, if 
loose material is left at the sides and the material at the extremity of the hori- 
zontal diameter is loose and offers little restraint, the pressure on the earth 
will not be distributed horizontally and the amount of bending moment will be 
materially different from that where careful bedding and tamping give an even 
distribution of bearing pressure over the bottom of the sewer. 

In case of a small sewer in a deep trench, the load upon the sewer may 
be materially less than the weight of the earth above, where the earth forms a 
hard compact mass and is held by pressure and friction against the sides of 
the trench. 

In case a culvert pipe is laid in an ordinary embankment by cutting down 
the sides slopingly, it is evident that the load which comes upon the pipe will 
be materially less than the weight of the earth immediately above it. If a 
culvert pipe replaces a trestle and the filling is allowed to run down the slope, 
the direction and amount of the pressure against the pipe will differ consider- 
ably from that which obtains in a trench or in the case of a level filling. It is 
possible in the latter case that the smaller amount of settlement of the earth 
directly over the culvert pipe, due to the greater depth of earth on the adjacent 
sections, may allow a greater proportion of the load to rest upon the culvert 
pipe than would ordinarily be assumed. 

Attention should be called to the fact that the distribution of the pressure 
by means of earth under and over a ring assumes that the earth is compressed 



Concrete Reinforcement 101 



in somewhat the same way as when other material of construction is given 
compression. Unless the earth has elasticity, the distribution of pressure can- 
not occur. To secure the uniform distribution assumed, the ring itself must 
give enough to allow for the movement of the earth which takes place under 
pressure. This is especially true with reference to the presence and utilization 
of lateral restraint, and a ring which does not give laterally, as for example a 
plain concrete ring will not develop lateral pressure in the adjoining earth 
under ordinary conditions of moisture and filling to any great extent. As the 
conditions of earth and moisture produce mobility and approach hydrostatic 
conditions, the necessity for this elasticity and movement do not exist, but 
here the lateral pressure approaches the vertical pressure in amount and the 
bending moments become relatively smaller. 

The discussion is sufficiently extended to indicate the importance of care 
in bedding culvert pipe and sewers and in filling over them, and to indicate 
the great difference in the amount of bending moment developed with different 
conditions of bedding and filling. Where there is any question of needed 
strength, it will be money well expended to use care and precaution in bedding 
the pipe and in filling around and over it. I am convinced that a little extra 
expense will add considerable stability, life, strength and safety to such 
structures, far out of proportion to the added cost. It is possible that under 
careful conditions of laying, lighter structures may be used with a saving in 
the cost of construction. 

Summary 

From the tests and the discussions it would seem evident that among the 
facts brought out are the following : 

The reinforced concrete rings in the concentrated load tests held their 
maximum loads or about their maximum loads through a considerable deflec- 
tion, thus showing a quality which is of value when changes in earth conditions 
permit a gradual yielding of the surrounding earth. The calculated restraining 
moment agrees fairly well with the calculated bending moment. 

The reinforced concrete rings and pipes tested under distributed load made 
a satisfactory showing. The so-called critical failure may occur by either 
tension failure in the steel or a diagonal tension failure (ordinarily called shear- 
ing failures) in the concrete. A flattened arc for the reinforcement where it 
approaches the inner face is of assistance and stirrups may be of some value. 
Beyond the critical load the reinforcement is of sendee in distributing the 
cracks and in holding the concrete together. Final failure is by crushing of 
the concrete in much the same way as was obtained with the plain concrete 
rings. The additional strength beyond the critical load may be taken into con- 
sideration in selecting the factor of safety or working strength. 

The restraint of the sand in the tests is very important, and the effect is 
to reduce the bending moment developed by a given vertical load, or, as it 



102 American Steel and Wire Company 

would be commonly stated, to add strength to the pipe. The degree of 
permanency of this side restraint is uncertain. It seems evident in these tests 
that the distribution of the pressure, both horizontal and vertical, was not 
uniform, and that with the usual method of placing a pipe in an embankment, 
and especially when other materials than sand are used, the distribution would 
be even less uniform than here found. In view of this it will be well in making 
calculations and designs to use the formula T "L- Wd for the bending moment, 
thus considering that the side of restraint is offset by the uneven distribution 
of the load, any surplus from this being considered merely an additional margin 
of safety. For pipes poorly bedded and filled a larger bending moment than 
yL- Wd should be used. 

The method of bedding and laying pipes and the nature of the bed and 
the surrounding earth have a great effect upon the bending moment developed 
and upon the resistance of the pipe to failure. If the method of laying, or the 
hardness of the soil below, or the condition of the settlement of the pipe is such 
that the pipe is supported only or mainly along an element of the cylinder at 
the bottom, the bending moment developed will be greatly increased over that 
of a uniformly distributed support. If the greatest supported pressure comes at 
points well to the side of this bottom element, as may be obtained by careful 
bedding, the bending moment is reduced. It is also plain that the bell should 
be left free from pressure at the bottom. It is possible that the presence of 
the bell detracts from the strength of the pipe. Any action in filling which 
increases the lateral restraint against the pipe will add to the security of the 
structure. 



Concrete Reinforcement 



103 




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104 



American Steel and Wire Company 




Typical Sewer Section Reinforced with One Layer Triangle Mesli Reinforcement. 

Note Continuous Reinforcement 



Concrete Reinforcement 



105 



1/1 i\ A A A A A A A A A A 



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106 



American Steel and Wire Company 






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MAY, 1918 

Superseding issue of January 1917 
Canceling certain pages of Engineer*! 
Handbook and book on Pavements and 
Roadways as described below. 

Subject to Change without Notice. 



American Steel & Wire Company's 



^5 
GRAND 



tfs 



Triangle Mesh 



lE!3r Concrete 



^m. 



Supreme Award 
of Merit 



Reinforcement 



Revised Specifications 

We have abandoned the manufacture of all styles of 
Concrete Reinforcement described on pages 108, 109, 110, 
111 and 112, of our Engineer's Handbook, and pages 
87, 88, 89, 90, 91, and 92 of our book on Pavements and 
Roadways and all specifications therein listed are hereby 
withdrawn; the following specifications are substituted. 

The continually increasing number of users 
testifies to the fact that Triangle Mesh 
Reinforcement is a convenient, economical 
and safe form of concrete reinforcement. 
Primarily, for the benefit of the user, the 
standard specifications are now revised so as 
to produce a fabric that is even more con- 
venient, more economical and equally safe. 

The principal changes are as follows: 
(1) New styles selected and so arranged in 
tables as to give comparatively uni- 
form increases in sectional area. 




(2) 



4-Inch Mesh 



(3) 



(4) 

(5) 



Styles are designated by numbers which 
correspond to the sectional areas. 
Example: Style Number 208 has a 
sectional area of steel of .208 square 
inches per foot width of fabric. (See 
Table Number 1.) 

Standard widths revised to a basis of 
equal multiples of 4 inches. (See Table 
Number 4.) 

Cross wire spacing of 2 inches eliminated. 

Cross wire spacing of 8 inches added. 
(See Tables Numbers 2 and 3.) 



American Steel & Wire Company 



Table No. 4 

Areas in Square Feet per Roll of Triangle 
Mesh Reinforcement 



Width of Roll 


Square Feet of Reinforcement in Roll 


Inches 










150-foot Roll 


200-foot Roll 


300-foot Roll 


16 


200 


267 


400 


20 


250 


333 


500 


24 


300 


400 


600 


28 


350 


467 


700 


32 


400 


533 


800 


36 


450 


600 


900 


40 


500 


667 


1000 


44 


550 


733 


1100 


48 


600 


800 


1200 


52 


650 


867 


1300 


56 


700 


933 


1400 



For the lighter styles, rolls of any of the above lengths may be used. Material 
of medium weights is recommended to be used in 150 or 200-foot lengths, while with 
the heaviest styles it is more conveniently handled in rolls containing 150-foot lengths. 



American Steel & Wire Company 



LIST OF PRODUCTS 



Amerite and Amerioore Rubber Covered Wire 
American Wire Rope 

Aeroplane Wire and Strand 
Piano Wire 
Pipe Organ Wire 
Mattress Wire 
Weaving Wire 
Ignition Wire 
Broom Wire 
Flat Wire— Flat Cold Rolled Steel 
Fence Wire 

Spoke Wire for Wire Wheels 
Electrical Wires and Cables 
Wire Hoops 
Rail Ronds 
Bale Ties 



Wire of Every Description 
Separate illustrated catalogue issned for each of these products. 

Sales Offices 



Aerial Tramways 
Tacks 

Auto Towing Cable 
Nails, Staples* Spikes 
Barbed Wire 
Woven Wire Fences 
Fence Gates 
Steel Fence Posts 
Concrete Reinforcement 
Springs 
Juniata Horseshoes and Calke 
Sulphate of Iron 
Wire Rods 
Screw Stock 
Cold Drawn Steel- 
round, square, hexagon, 
special shapes 
Poultry Netting 
Furnished free upon request* 



CHICAGO 208 So. La Salle Street 

NEW YORK 30 Church Street 

WORCESTER 94 Grove Street 

BOSTON 120 Franklin Street 

PHILADELPHIA Widener Building 

PITTSBURGH Frlck Building 

BUFFALO 337 Washington Street 

DETROIT Foot of First Street 

CINCINNATI Union Trust Building 

Export Representative: U. S. 
Pacific Coast Representative: 



Form No. 3907 



San Francisco 



Los Angeles 



CLEVELAND Western Reserve Building 

BALTIMORE 32 So. Charles Street 

WILKESBARRE, PA Miners Bank Building 

ST. LOUIS 3d National Bank Building 

ST. PAUL-MINNEAPOLIS . Pioneer Bldg., St. Paul 
OKLAHOMA CITY . . State National Bank Building 

BIRMINGHAM, ALA Brown-Marx Building 

DENVER 1st National Bank Building 

SALT LAKE CITY Walker Bank Building 

Steel Products Co., New York 

U. S. Steel Products Company 



Portland 



Seattle 



Concrete Reinforcement 



113 



The Steel Wire Ga£e* and Different 
Sizes of Wire 



Diameter 
Inches 


Steel Wire 
Gage* 


Diameter 
Inches 


Area, Square 
Inches 


Pounds 
per foot 


Pounds 
per Mile 


Feet 
per Pound 


1 

2 

15 
32 


7o 


.5000 
.4900 
.46875 


. 19635 

. 18857 
. 17257 


.6668 
.6404 
.5861 


3521. 
3381. 
3094. 


1.500 
1.562 
1.706 


7 
16 


% 
7o 


.4615 
.4375 
.4305 


. 16728 
. 15033 
. 14556 


.5681 
.5105 
.4943 


2999. 
2696. 
2610. 


1.76 

1.959 

2.023 


13 
32 

3 

8 


7o 


.40625 

.3938 

.3750 


. 12962 
.12180 
.11045 


.4402 
.4136 
.3751 


2324. 
2184. 
1980. 


2.272 
2.418 
2.666 


11 
32 


7o 
7o 


.3625 

.34375 

.3310 


. 10321 

.092806 
.086049 


.3505 
.3152 
.2922 


1851. 
1664. 
1543. 


2.853 
3.173 
3.422 


5 
16 




l 


.3125 
.3065 
.2830 


.076699 
.073782 
.062902 


.2605 
.2506 
.2136 


1375. 
1323. 
1128. 


3.839 
3.991 
4.681 


9 
32 

1 
4 


2 


.28125 

.2625 

.2500 


.062126 
.054119 
.049087 


.2110 
.1838 
.1667 


1114. 
970.4 
880.2 


4.74 
5 . 441 
5.999 


7 
32 


3 

4 


.2437 
.2253 
.21875 


.046645 
.039867 
.037583 


.1584 
.1354 
.1276 


836.4 
714 8 
673 .9 


6.313 

7 . 386 
7.835 


3 
16 


5 
6 


.2070 
.1920 
.1875 


.033654 
.028953 
.027612 


.1143 
.09832 
.09377 • 


603.4 
519.2 
495.1 


8.750 
10.17 
10.66 


5 
32 


7 
8 


.1770 
.1620 
.15625 


.024606 
.020612 
.019175 


.08356 
.07000 
.06512 


441.2 
369.6 
343.8 


11.97 
14.29 
15.36 


1 
8 


9 
10 


.1483 
.1350 
.125 


.017273 
.014314 
.012272 


.05866 
.04861 
.04168 


309.7 
256 . 7 
220.0 


17.05 
20.57 
24.00 


3 
32 


11 
12 


.1205 
. 1055 
.09375 


.011404 

.0087417 
.0069029 


.03873 

.02969 
.02344 


204.5 
156.7 
123.8 


25.82 
33.69 
42.66 




13 
14 
15 
16 

17 


.0915 
.0800 
.0720 
.0625 
.0540 


.0065755 
.0050266 
.0040715 
.0030680 
.0022902 


.02233 
.01707 
.01383 
.01042 
. 007778 


117.9 
90.13 
73.01 
55.01 

41.07 


44.78 
58.58 
72.32 
95.98 
128.60 



*Formerly called the "American Steel & Wire Co's Gage." The name "Steel Wire Gage" is 
adopted as standard for all steel wire upon recommendation of the United States Bureau of Standards. 



114 



American Steel and Wire Company 



Comparative Sizes of the Different Wire Gages, 
in Decimals of an Inch 



No. of 
Wire Gage 


Steel Wire 
Gage* 


American 

Wire Gagef 

(B.&S.) 


Birmingham 

or 

Stubs 


British 
Imperial 
Standard J 


Old English 

or 

London 


French 


0000000 


.4900 






.500 






000000 


.4615 


.58000 


. 


.464 






00000 


.4305 


.51650 


.500 


.432 






0000 


.3938 


.46000 


.454 


.400 


.4540 




000 


.3625 


.40964 


.425 


.372 


.4250 




00 


.3310 


.36480 


.380 


.348 


.3800 







.3065 


.32486 


.340 


.324 


.3400 




1 


.2830 


.28930 


.300 


.300 


.3000 


.0325 


2 


.2625 


.25763 


.284 


.276 


.2840 


.040 


3 


.2437 


.22942 


.259 


.252 


.2590 


.050 


4 


.2253 


.20431 


.238 


.232 


.2380 


.0625 


5 


.2070 


.18194 


.220 


.212 


.2200 


.068 


6 


.1920 


.16202 


.203 


.192 


.2030 


.083 


7 


.1770 


.14428 


.180 


.176 


.1800 


.097 


8 


.1620 


.12819 


.165 


.160 


.1650 


.110 


9 


,1483 


.11443 


.148 


.144 


.1480 


.120 


10 


.1350 


.10189 


.134 


.128 


.1340 


.135 


11 


.1205 


.09074 


.120 


.116 


.1200 


.149 


12 


.1055 


.08081 


.109 


.104 


.1090 


.162 


13 


.0915 


.07196 


.095 


.092 


.0950 


.172 


14 


.0800 


.06408 


.083 


.080 


.0830 


.185 


15 


.0720 


.05706 


.072 


.072 


.0720 


.197 


16 


.0625 


.05082 


.065 


.064 


.0650 


.212 


17 


.0540 


.04525 


.058 


.056 


.0580 


.225 


18 


.0475 


.04030 


.049 


.048 


.0490 


.238 


19 


.0410 


.03589 


.042 


.040 


.0400 


.250 


20 


.0348 


.03196 


.035 


.036 


.0350 


.263 


21 


.0317 


02846 


.032 


.032 


.0315 


.279 


22 


.0286 


.02535 


.028 


.028 


.0295 


.290 


23 


.0258 


.02257 


.025 


.024 


.0270 


.303 


24 


.0230 


.02010 


.022 


.022 


.0250 


.316 


25 


.0204 


.01790 


.020 


.020 


.0230 


.331 


26 


.0181 


.01594 


.018 


.018 


.0205 


.342 


27 


.0173 


.01420 


.016 


.0164 


.01875 


.356 


28 


.0162 


.01264 


.014 


.0148 


.01650 


.371 


29 


.0150 


.01126 


.013 


.0136 


.01550 


.383 


30 


.0140 


.01003 


.012 


.0124 


.01375 


.394 


3L 


.0132 


.00893 


.010 


.0116 


.01225 


.408 


32 


.0128 


.00795 


.009 


.0108 


.01125 


.419 


33 


.0118 


.00708 


.008 


.0100 


.01025 


.431 


34 


.0104 


.00630 


.007 


.0092 


.00950 


.448 


35 


.0095 


.00561 


.005 


.0084 


.00900 


.458 


36 


.0090 


.00500 


.004 


.0076 


.00750 


.472 


37 


.0085 


.00445 


. 


.0068 


.00650 


.485 


38 


.0080 


.00396 




.0060 


.00575 


.499 


39 


.0075 


.00353 




.0052 


.00500 


.509 


40 


.0070 


.00314 


• • 


.0048 


.00450 


.524 



*Forrnerly called the '•American Steel & Wire Co.'s Gage." The name '"Steel Wire 
Gage" adopted as standard for all steel wire upon recommendatiou of the United States 
Bureau of Standards. 

fFor copper wires and wires of other metals than steel the gage universally recognized 
in the United States is the "American Wire Gage." also known as the Brown & Sharpe. 
No confusion need arise between the Steel Wire Gage and the American Wire Gage, 
because the fields covered by the two gages are distinct and definite. 

JAlso called New British or English Legal Standard. 



Concrete Reinforcement 



115 



Weights and Areas of Square and Round Bars and 
Circumferences of Round Bars 

One Cubic Foot of Steel Weighing 489.6 Pounds 



Thickness or 


Weight of 


Weight of 


Area of Square 


Area of Round 


Circumference 


Diameter in 


Square Bar 


Round Bar 


Bar in Square 


Bar in Square 


of Round Bar 


Inches 


1 Foot Long 


1 Foot Long 


Inches 


Inches 


in Inches 




1 

1 ft 


.013 


.010 


.0039 


.0031 


.1963 


1 • 


.053 


.042 


.0156 


.0123 


.3927 


3 


.119 


.094 


.0352 


.0276 


.5890 


X 


.212 


.167 


.0625 


.0491 


.7854 


5 
TIT 


.333 


.26L 


.0977 


.0767 


.9817 


H 


.478 


.375 


.1406 


.1104 


1.1781 


i 


.651 


.511 


.1914 


.1503 


1.3744 


'A 


.850 


.667 


.2500 


.1963 


1.5708 


9 
T"ff 


1.076 


.845 


.3164 


.2485 


1.7671 




1.328 


1.043 


.3906 


.3068 


1.9635 


ii 

TB" 


1.608 


1.262 


.4727 


.3712 


2.1598 


u 


1.913 


1.502 


.5625 


.4418 


2.3562 


18 
TIT 


2.245 


1.763 


.6602 


.5185 


2.5525 


# 


2.603 


2.044 


.7656 


.6013 


2.7489 


16 


2.989 


. 2.347 


,8789 


.6903 


2.9452 


1 


3.400 


2.670 


1.0000 


.7854 


3.1416 


1 
TTf 


3.838 


3.014 


1.1289 


.8866 


3.3379 


^ 


4.303 


3.379 


1.2656 


.9940 


3.5343 


3 


4.795 


3.766 


1.4102 


1.1075 


3 . 7306 


X 


5.312 


4.173 


1.5625 


1.2272 


3.9270 


5 

T~6 


5.857 


4.600 


1.7227 


1.3530 


4.1233 


# 


6.428 


5.049 


1.8906 


1.4849 


4.3197 


7 


7.026 


5.518 


2.0664 


1.6230 


4.5160 


l A 


7.650 


6.008 


2.2500 


1.7671 


4.7124 


9 
T6" 


8.301 


6.520 


2.4414 


1.9175 


4.9087 


# 


8.978 


7.051 


2.6406 


2 0739 


5.1051 


11 


9.682 


7.604 


2.8477 


2.2365 


5.3014 


X 


10.41 


8.178 


3.0625 


2.4053 


5.4978 


3 


11.17 


8.773 


3.2852 


2.5802 


5.6941 


7 /s 


11.95 


9.388 


3.5156 


2.7612 


5.8905 


1 5 


12.76 


10.02 


3.7539 


2.9483 


6.0868 



116 



American Steel and Wire Company 




Wall 



' /Vote hinge joint on each longitudinal member 



Wal 




Cage farmed of 
Triangular Mesh Fabric 



Wall with Pilaster 



Plaster on metal lath attached to studding of Trianguiar Mesh Reinforcement 



lirrrrfirgS 



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Sir' a gjfrr^ i ^^T . iy^S 



Air Space! 



Plaster Partition Wall 
Wall Construction 



Concrete Reinf orcein ent 



117 



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Concrete Reinforcement 127 



Test No. 60 Printed Report No. 9 

Report of a 

Fire, Load and Water Test 

made upon a 

Triangular Reinforced Concrete Floor System 

Constructed by American Steel and Wire 

Company, at the Fire Testing 

Station, Columbia University 

New York City 



New York, March 5, 1908 



Test Conducted by Ira H. Woolson, E. M. 

Adjunct Professor of Civil Engineering 

in Co-operation with the City Building Rureaus 



128 



American Steel and Wire Company 






















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130 American Steel and Wire Company 



Method of Construction 

The test was conducted in test house No. 2, which is a reinforced cinder 
concrete structure 14 x 20' on the inside. It is supplied with six suitable 
chimneys at the top and draft openings through the wall at the bottom. The 
fire grate is located 2' 6" above the ground level. 

The floor construction under test formed the temporary roof of the test 
house. The under side or ceiling being 9' 6" above the grate. 

Two types of floor arches were tested, one with a span of 8 feet and the 
other a span of 5 feet. 

The 8-foot span occupied the south side of the test chamber and was 
made of cinder concrete 5 inches thick, reinforced a\ ith the metal fabric of 
the American Steel & Wire Company, known as Style No. 38, the disposi- 
tion of which is indicated in the attached blue prints and photograph No. 1. 
This metal fabric consisted of three twisted strands of No. 4 steel wire, spaced 
and secured every four inches by No. 12 }4 diagonal steel cross wire. 

The 5-foot span occupied the north side of the test chamber and was 
made of cinder concrete 4 inches thick, reinforced with American Steel & 
Wire Company's fabric, Style No. 23. The metal fabric in this span con- 
sisted of one strand of j^-inch steel wire, spaced and secured every four 
inches by diagonal wires the same as in the fabric of the 8-foot span. The 
character of this fabric can be seen in the middle of photograph No. 1, where 
it laps over the two central beams. The fabric in the spans was placed 1*4 
inches above the bottom surface of the concrete. 

The 8-foot span was supported by 12" 40-pound I-beams, and the 5-foot 
span by 10" 25-pound I-beams. These beams were protected by two inches 
of concrete below the bottom flange of the beams, and one and one-half inches 
of concrete at each side of the lower flanges. 

The concrete was held in place by American Steel & Wire Company's 
fabric, Style No. 8, consisting of one strand of No. 12^2 wire secured every 
four inches by No. 14 diagonal cross wires. 

The concrete used in the construction was a 1-2-5 mixture of Portland 
cement, clean sharp sand and boiler cinders. 

Specimen blocks of this mixture were made at the time that the material 
was being placed, and were tested for strength when about eleven weeks old. 
They gave an average value of 1,000 pounds per square inch. 

Full details of the construction are given in the attached drawings and 
photographs. 

The 5-foot span was put in place December 18, 1907, and the 8-foot span 
on January 25, 1908. The former was therefore about eleven weeks old, and 
the latter six weeks at test. 



Concrete Reinforcement 131 



Owing to the fact that it was stormy and freezing weather most of the 
period the concrete was setting, a salamander was kept burning in the test 
building the greater portion of the time. 

Purpose of the Test 

The purpose of the test was to determine the effect of a continuous fire 
below the floor for four hours at an average temperature of 1700 degrees 
Fahr., the floor carrying at the same time a distributed load of 150 pounds 
per square foot; at the end of the four hours the under side of the floor (or 
ceiling) while still red hot to be subjected to a 1^-inch stream of cold water 
at short range, through 100 feet of hose under 60 pounds pressure at the 
nozzle for five minutes, then the upper side of the floor (which forms the roof 
of the test building) to be flooded at low pressure ; afterwards the stream to be 
again applied at full pressure on the under side for five minutes longer. 

Deflection of beams and floor to be measured continuously during the test. 
The load then to be removed and after the floor becomes cold, it shall be 
reloaded to 600 pounds per square foot, and deflections noted. 

Temperatures 

The temperatures of the fire were obtained by three electric pyrometer 
couples suspended through the floor from above and hanging about inches 
below the ceiling. The location of the couples is indicated on the temperature 
curve sheet. 

Readings were made upon each couple every three minutes. The fuel 
used was dry cord wood, the frequency of firing being determined by the 
temperature of the test chamber. The " Log of Temperature Reading," together 
with plotted curve for the middle couple, is herewith attached. 

Deflections 

The deflections which occurred during the test were measured by a Y 
level, reading upon rods located upon the ends and middle of each beam, also 
upon the middle of the floor arches. The " Table of Deflections " gives full 
information regarding the variation in level of each point through the test, and 
the " Deflection Diagram " shows the relative position of the three members 
graphically at different times. 

Water 

The water was applied by firemen with an engine detailed from 143d 
Street and Eight Avenue fire station, under direction of Battalion Chief 
Ecward S. Root. The pressure gage was carefully watched, and 60 pounds 
maintained at the nozzle. 

In applying the water, the stream was thrown back and forth over the whole 
ceiling as much as possible, and not allowed to strike continuously on one spot. 
After five minutes' application the pressure was reduced to about 30 pounds 



132 American Steel and Wire Company 

and the top of the floor flooded, then the steam was applied to the ceiling again 
at full pressure for five minutes longer. Total time of application at full pressure 
was ten minutes. 

Through an error the firemen brought with them a 1^-inch nozzle instead 
of the regulation 1^-inch diameter. This larger nozzle was therefore used, 
which made the stream somewhat more severe than usual. 

Results of the Test 

About one hour after starting the fire, three cracks appeared on the top of 
the floor or roof of the building. Two of these cracks were parallel with and 
nearly over the two supporting beams of the 8-foot span, and the third was 
similarly located along the middle beam of the 5-foot span. These cracks 
gradually opened during the test to a maximum width of about -^ of an inch. 
Some water boiled out of the concrete and ran out upon the roof. During the 
latter part of the test, a few small diagonal cracks developed near the ends of 
beams, and ran across the floor slabs towards the middle of the spans. 

All of these cracks were evidently due to expansion. They appeared to 
be on the upper surface only. The under side of the floor or ceiling of the 
test chamber was in perfect condition, so far as could be observed, up to the 
application of water. The water scored the surface somewhat in front of the 
doors where its action was most severe, but only to a depth of about one inch 
as a maximum. Considerable of the concrete thus washed out was along the 
line of the cracks between the centering boards where the cement had evidently 
been carried away by the escaping water at the time the floor was placed. 
This is a defect that could be easily avoided. 

The wire mesh encasing the bottom of the middle I-beam of the 8-foot 
span was exposed for about three feet near the middle of the beam, and the 
flange of the beam itself was bare for eighteen inches. This was the only metal 
exposed by the application of water. 

There was one crack 4 feet long in the central portion of the 8-foot 
span about one foot from the middle beam and running parallel with it. 

There were several small cracks across the bottom of the beams, but the 
concrete remained firm and secure. 

As a whole the ceiling was in excellent condition at the completion 
of the test. 

The maximum deflection at the middle of the 8 and 5-foot span 
during the fire was l^ and \\ inches, respectively. The larger part of this 
was recovered when the floor cooled, and the application of the final load of 
600 pounds per square foot, increased the deflection on the larger span only 
-^-inch, and on the smaller span y^-inch. 



Concrete Reinforcement 133 



No new cracks developed as a result of the loading, and there was no 
evidence that the floor was distressed. 

The total permanent deflection of the two spans after entire removal of 
load was $& inch for the 8-foot span and j{ inch for the 5-foot span. 

The test was conducted in co-operation with the Bureau of Buildings of 
this city, and the installation of the floor was observed by representatives 
from the bureaus in the various boroughs, also from Philadelphia. 

The test was witnessed by the following Building Bureau Engineers : 

A. Schwartz, Borough of Manhattan. 
H. Vanatta, Borough of Bronx. 
Harry Brown, Borough of Richmond. 

W. G. Button, Bureau of Building Inspection, Philadelphia, Pa. 

Spencer B. Hopkins, Bureau of Buildings, Providence, R. I. 

The American Steel & Wire Company were represented by 

T. H. Taylor, New York Office. 

H. S. Doyle, Chicago Office. 

L. A. Dietrich, New York Office. 

R. H. Pratt, New York Office, and several others. 

A large number of spectators were present, among them being the following: 

Rudolph P. Miller, Consulting Engineer, 527 Fifth Avenue, New York. 
Colonel Hodges, Chief Engineer, Isthmian Canal Commission, Washing- 
ton, D. C. 

R. All worth, Assistant Chief Engineer, Washington, D. C. 

Major Langfitt, U. S. Engineer Corps, Washington, D. C. 

G. H. Stewart, Rep. Ins. Engineer, 120 Liberty Street, New York. 

G. E. Stecher, Rep. Ins. Press, 56 Cedar Street, New York. 

H. R. Leonard, Engineer, Penn. R. R., Philadelphia, Pa. 

J. F. Murray, Engineer, Penn. R. R., Philadelphia, Pa. 

B. H. Davis, Asst. Engineer, D., L. & W. R. R., Hoboken, N. J. 
J. B. French, Engineer, L. I. R. R., Jamaica, L. I., N. Y. 

R. W. How, Inspector, L. I. R. R., Jamaica, L. I., N. Y. 

Geo. P. Enke, Inspector, German- American Insurance Co., New York. 

Frank B. Gilbreth, Cont. Eng., 34 West 26th Street, New York. 

P. H. Bevier, Engineer, National Fireproofing Co., New York. 

S. P. Waldron, American Bridge Co., 42 Broadway, New York. 

W. H. Olthoff, U. S. Steel Prod. Exp. Co., 24 State Street, New York. 

J. Traverse, Neuchatel Asphalt Co., 265 Broadway, New York. 

E. Merrick, Merrick Fireproof Co., 11 Broadway, New York. 

P. E. Bertin, 30 West 33rd Street, New York. 

W. B. Ruggles, Curtin-Ruggles Co., 39 Cortlandt Street, New York. 

L. R. Christie, Curtin-Ruggles Co., 39 Cortlandt Street, New York. 

Capt. J. F. Shea, Jerome Avenue and 183d Street, New York. 

Fuller Claflin, Architect, 1440 Broadway, New York. 

J. P. H. Perry, Turner Construction Co., 11 Broadway, New York. 

C. U. Carpenter, Pres. Herring-Hall-Marvin Safe Co., 400 Broadway. 
New York. 

J. G. Ellendt, J. G. Ellendt Co., 1 Madison Avenue, New York. 

W. H. Wheelock, Douglas Robinson Co., 146 Broadway, New York. 

G. E. Walsh, 555 West 183d Street, New York. 

Respectfully submitted, 

IRA H. WOOLSON 



134 



American Steel and Wire Company 



DErLECT/OM 2) JAG 7? Art 



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Deflection Diagram for 5-foot Span 






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Deflection Diagram for 8-foot Span 



Concrete Reinforcement 



135 



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136 



American Steel and Wire Company 



Deflection Readings 

Note — For location of rods see "Deflection Diagrams." Deflections are given in 
sixteenths of an inch ; those preceded by a minus sign are rises, those by no sign are falls. 

Deflections read by J. C. Jenkins. 



March 3, 1908 
No load 

10.00 a. m 

March 4 

Load, 150 pounds per square 
foot. Start of fire 

8.30 a. m 

8.50 a. m. ...... 

9.20 a. m 

9.50 a. m 

10.20 a. m 

10.50 a. m ' . 

11.20 a. m 

11.50 a. m 

12.30 a. m 

End of fire 

March 5 

Floor cool; load, 150 pounds 

per square foot, 8.45 a. m. . 
Load, 600 pounds per square 

foot on 5-foot span, 1.30 a. m. 
Load, 600 pounds per square 

foot on 8-foot span, 2.40 a. m. 
No load 

4.30 a. m 





2 

3 

3 

4 

7 

10 

13 

15 



8 



G 



9 10 11 




4 
7 

10 
15 
19 
26 
30 
84 



8 

7 

13 

6 





-2 
—3 

3 
—3 

3 
—3 
—3 

3 



1 

2 

2 

2 

6 

9 

14 

17 

20 






— 1 

—2 
2 
-2 











3 

4 

7 

12 

16 

21 

24 

28 




— 1 
—2 
—2 
—2 
—3 
—3 
—3 







2 

3 

4 

8 

11 

13 

14 






— 1 

1 
—2 

■2 
—3 
—3 
—4 



Concrete Reinforcement 



137 



Corrected Total Deflections 

For Middle of Beam, taking into Account the Rise of Ends of Beams 

8-Foot Span 





Rod 2 


Rod 4 


Rod 6 




South Beam 


Center Floor Slab 


Center Beam 




Inches 


Inches 


Inches 


March 4 








End of fire, 12.30 p. m. . . . 


1 a 


•1 1 


1 al 

X T2 


March 5 








Floor cool ; load, 1 50 pounds 








per square foot, 8.45 a. m. 


3 

16 


y% 


>A 


Load, GOO pounds per square 








foot, 2.40 p. m 


9 


9 
IS 


7 


No load, 4.30 p. m 





H 


1 



5-Foot Span 



March 4 

End of fire, 12 30 p. m. . . . 

March 5 

Floor cool ; load, 150 pounds 

per square foot, 8 45 a. m. 
Load, 600 pounds per square 

foot, 1.30 p. m 

No load, 4.30 p m 



Rod 

Center Beam 
Inches 



x 32 



7 

3¥ 
_1_ 

1 6 



Rod 8 

Center Floor Slab 

Inches 



11 

16 



¥^ 



11 
33 

X 



Rod 10 

North Beam 

Inches 



IX 



3 

T6" 



3 
TS 





Note — The results are obtained as follows : 

For all beam deflections when the ends rise and the middle falls, add the middle 
deflections to the mean of the two end rises. When the ends and middle fall, subtract. 



138 



American Steel and Wire Company 



Log of Temperature Readings 

Fire Test 

The American Steel & Wire Company 
Fireproof Floor Construction 

Temperatures Read by J. S. Macgregor, M. S. 



Time 


Couple No. 1 


Couple No. 2 


Couple No. i\ 




8.30 Start 










33 


205 


394 


261 




36 


8J5 


1259 


828 




39 


935 


1311 


1130 




42 


1019 


1380 


1254 




45 


1156 


1397 


1311 




48 


1248 


1457 


1324 




51 


1346 


1494 


1374 




54 


1385 


1530 


1415 




57 


1447 


1586 


1397 




9.00 


1524 


1622 


1415 




03 


1562 


1635 


1426 




06 


1584 


1647 


1462 




09 


1610 


1659 


1499 




12 


1635 


1671 


1545 




15 


1659 


1719 


1562 




18 


1647 


1731 


1573 




21 


1719 


1755 


1597 




24 


1719 


1743 


1586 




27 


1707 


1755 


1622 




30 


1719 


1767 


1635 




33 


1779 


1814 


1659 




36 


1802 


1825 


1719 




39 


1732 


1756 


1708 




42 


1768 


1850 


1768 




45 


1838 


1844 


1774 




48 


1844 


1850 


1792 




51 


1780 


1844 


1768 




9.54 


1720 


1780 


1708 




57 


1732 


1756 


1690 




10.00 


1804 


1827 


1756 




03 


1744 


1756 


1732 




06 


1756 


1774 


1744 




09 


1780 


1821 


1804 




12 


1768 


1780 


1756 




- 15 


1732 


1738 


1696 




18 


1684 


1708 


1732 





Concrete Reinforcement 



139 



Time 


Couple No. 1 


Couple No. 2 


Couple No. 3 


10.21 


1756 


1792 


1744 




24 


1741 


1789 


1717 




27 


1836 


1830 


1765 




30 


1857 


1895 


1765 




33 


1707 


1753 


1693 




36 


1765 


1777 


1717 




39 


1847 


1853 


1824 




42 


1830 


1836 


1813 




45 


1753 


1789 


1741 




■ 48 


1741 


1765 


1729 




51 


1847 


1801 


1777 




54 


1819 


1830 


1824 




57 


1836 


1847 


1830 




11.00 


1824 


1836 


1813 




03 


1705 


1729 


1671 




06 


1777 


1765 


1729 




09 


1789 


1836 


1777 




12 


1777 


1824 


1789 




15 


1705 


1693 


1771 




18 


1795 


1807 


1747 




21 


1819 


1830 


1783 




24 


1771 


1795 


1771 




27 


1687 


1711 


1650 




11.30 


1638 


1650 


1625 




33 


1640 


1638 


1644 




36 


1640 


1625 


1644 




39 


1687 


1723 


1675 




42 


1711 


1735 


1717 




45 


1759 


1795 


1771 




48 


1675 


1723 


1675 




51 


1771 


1795 


1723 




54 


1747 


1771 


1723 




57 


1759 


1759 


1711 




12.00 


1612 


1648 


1601 




03 


1745 


1743 


1687 




06 


1757 


1769 


1745 




09 


1721 


1732 


1697 




12 


1600 


1635 


1622 




15 


1757 


1769 


1757 




18 


1740 


1758 


1734 




21 


1704 


1728 


1692 




24 


1618 


1607 


1579 




27 


1629 


1562 


1593 




30 


1608 


1593 


1580 




Averages .... 


1655 


1704 


1644 





140 



American Steel and Wire Company 




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cs a 

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2 ° 

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Concrete Reinforcement 



141 




Method of Anchoring- Metal at Edge of Floor 
Concrete in riace on 8-foot Span 




Fnrterside of Floor Before Test, Showing Two Middle Beams and 

8 -foot Span 



142 



American Steel and Wire Company 




.a 



85 

W 
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;- 

5 

5« 
oc 

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Concrete Reinforcement 



143 




Building During the Fire 




Firemen Applying Water 



144 



American Steel and Wire Company 




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Concrete Reinforcement 



145 




Load of 600 Pounds per Square Foot on 8-foot Span 




Load of 600 Pounds Per Square Foot on 5 -foot Span 



LIBRARY OF CONGRESS 



Index 



Page 
Adhesion between concrete and steel . 10 
Area, cross sectional, triangle mesh 

fabric . ., • -110, 111 

Different gages of wire . . .113 

Square and round bars . . 115 

In square feet per roll of triangle 

mesh fabric 112 



Bars, weights, areas and circumferences 



of square and round 


115 


Beams, rectangular 


66 


Tee . . . • • 


67 


Bonding old and new concrete 


37 


Concrete to steel . . .14, 


16 


Cement, analysis of ... 


40 


Classification of .... 


40 


Grappiers ...... 


43 


Natural 


42 


Portland ...... 


41 


Tuzzolan or slag .... 


43 


Sand ....... 


41 


Slow setting ..... 


42 


Vassy ...... 


42 


Required for one cubic yard of 




concrete ..... 58 


-65 


Required for one cubic yard of 




mortar ...... 


59 


Cinder versus stone concrete 


32 


Circumference of square and round bars 


115 


Coefficient of expansion 


16 


Of elasticity ..... 


34 


Columns, reinforced concrete . 90, 


91 


Tables of safe loads on . . 92, 


93 


Concrete, adhesion between steel and . 


16 


Bonding old and new 


37 


Cinder versus stone .... 


32 


Coefficient of expansion 


16 


Cost ....... 


19 


Elongation or stretch of 


35 


Relations between steel and . 13, 


15 


Strength 8, 9, 


21 


Teira cotta versus 


31 


Theory of reinforced . 


66 


Safe working stresses . 14, 74-85 


Corrosion, protection of steel or iron 




from . ' . 


26 


Cost, concrete 


19 


Gravel or broken stone 


20 


Labor 


20 


Sand . . .... 


20 



019 418 901 

Page 
Discoloration, causes of roughness and 46 

Earthquake, effect of California . . 17 

Efflorescence . . 55 

Elasticity, modulus or coefficient 

11, 15, 34 



of 

Elongations or stress in concrete 
Expansion, coefficient of 



Facing and finishing concrete surfaces 
Facing, brick . 

Masonry . . ' 

Mortar or grout . 

Pebble dash 

Stone . 

Tooled surface . 
Fire protection 
Fire in borax factory 
Fire, Baltimore 
Fire, load and water tes 
Forms, construction of 
Freezing, effect of 

Gravel, cost of .... . 

Labor, cost of . . . 

Load, concentrated vertical, on pipe 

Distributed vertical, on pipe 

Distributed vertical and horizontal, 
on pipe . 

Loads, working 

Lime, common 

Hydrated 

Hydraulic . 

Magnesian . 



35 
16 

46 

53 

. 52 

48, 49 

. 51 

. 52 

. 51 

30, 32 

. 30 

. 30 

127-145 

. 47 



38 

20 

20 
95 
96 

98 
13 
45 
45 
44 
45 



Materials, tables of quantities of . 58—65 

Modulus of elasticity . . . .11 

Moments, formulas for bending . . 67 

Bending moments in concrete pipe . 94 

Diagrams of bending moments in 

concrete slabs . . . 88, 89 

Resisting moments and calculation of 
stresses in pipes . . . . 9S 

Resisting moments in beams and 
slabs . . . 66, 67 

Tables of resisting moments of rein- 
forced concrete slabs . . 74—85 



Ornamental shapes 
Plastering concrete surfaces 



54 
51 



Concrete Reinforcement 



147 



Po'e, illustration of triangle mesh rein 

forced concrete telegraph 
Tost, illustration of triangle mesh rein 

forced concrete fence 
Properties of reinforced concrete . 
Properties of steel 

Pipes, mechanics of pipes and ring 
subjected to external pressure 
Bending moments and conditions of 

loading . 
Concentrated vertical load on . 
Distributed vertical load on 
Distributed vertical and horizontal 

loads on . 
Conditions of bedding and loading 

found in practice 
Resisting moment and calculation of 

stresses ..... 
Summary of tests 
Illustrations of concrete pipes rein- 
forced with triangle mesh reinforce- 
ment . . . . . 103 



Page 

117 

117 

7 

13 

94 

94 
93 
9G 

98 

99 

98 
101 

-107 



Reinforced concrete .... 6 

Reinforced concrete, properties of . 7 

Finishing surfaces . . . .46 

Theory of . . . . .66 

Reinforcing steel (see also Triangle 

Mesh Reinforcement) . . .23 

Report of fire, load and water test, 127-145 



Sand, cost of ..... 20 

Required for one cubic yard of con- 
crete ..... 58-65 

Required for one cubic yard of mortar 59 
Shear in rectangular beams . . .67 

.Slabs, explanation of tables for rein- 
forced concrete . . . .69 

Illustrations of reinforced concrete . 87 
Minimum depth of . . .86 

Square ...... 70 

Rectangular . . . . .71 

Tables of resisting moments of rein- 
forced concrete . . . 74-85 



Page 

Steel, adhesion between concrete and . 16 

Coefficient of expansion of . .16 

Fire protection of . . .30 

Grade of . . . . .25 

Protection from corrosion . . .26 

Properties of . . . .13 

Relations between concrete and . 16 

For reinforcing (see also Triangle 
Mesh Reinforcement) . . .23 

Stone, cost of ..... 20 

Amount required for one cubic yard 
of concrete .... 58-65 

Strength, compressive, concrete . 8, 21 
Tensile, concrete . . 9, 21 

Shearing, concrete . . . 9, 21 
Stresses, safe working stresses for 

concrete ...... 14 

Surfaces, finishing of reinforced concrete 46 

Tee-beams ...... 67 

Terra-cotta versus concrete . . .31 

Triangle Mesh Steel Wire Reinforce- 
ment 

Advantages of . . . . .5 

Description of . . . . 108, 109 

Tables showing number and gages of 
wires, areas per foot width, weights 
per 100 square feet, and areas in 
square feet per roll . 110, 111, 112 

Illustrations of uses of . . 118-126 
Illustrating use in concrete pipe, 103-107 

Veneer, cast concrete slab . . .54 

Walls, typical sections of reinforced 

concrete . . . . . .116 

Weights and areas of square and round 

bars . . . . . .115 

Weight of concrete . . . .69 

Weight of triangle mesh reinforce- 
ment 110, 111 

Of different sizes of wire . . . 113 

Working loads . . . . .13 

Stresses, safe . . . . .14 

Wire, gages, areas and weights . .113 

Comparative sizes of gages . . 114 



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